Add support for reserved seating (#1228)

* Initial work on seating * Add seat guids * Add product_list_top * CartAdd: Ignore item when a seat is passed * Cart display * product_list_top → render_seating_plan * Render seating plan in voucher redemption * Fix failing tests * Add tests for extending cart positions with seats * Add subevent_forms to docs * Update schema, migrations * Dealing with expired orders * steps to order change * Change order positions * Allow to add seats * tests for ocm * Fix things after rebase * Seating plans API * Add more tests for cart behaviour * Widget support * Adjust widget tests * Re-enable CSP * Update schema * Api: position.seat * Add guid to word list * API: (sub)event.seating_plan * Vali fixes * Fix api * Fix reference in test * Fix test for real
2019-06-25 11:00:03 +02:00
parent f79d17cb6a
commit 93089d87e3
77 changed files with 3689 additions and 164 deletions
--- a/src/pretix/api/serializers/cart.py
+++ b/src/pretix/api/serializers/cart.py
@@ -8,31 +8,33 @@ from rest_framework.exceptions import ValidationError

 from pretix.api.serializers.i18n import I18nAwareModelSerializer
 from pretix.api.serializers.order import (
-    AnswerCreateSerializer, AnswerSerializer,
+    AnswerCreateSerializer, AnswerSerializer, InlineSeatSerializer,
 )
-from pretix.base.models import Quota
+from pretix.base.models import Quota, Seat
 from pretix.base.models.orders import CartPosition


 class CartPositionSerializer(I18nAwareModelSerializer):
    answers = AnswerSerializer(many=True)
+    seat = InlineSeatSerializer()

    class Meta:
        model = CartPosition
        fields = ('id', 'cart_id', 'item', 'variation', 'price', 'attendee_name', 'attendee_name_parts',
                  'attendee_email', 'voucher', 'addon_to', 'subevent', 'datetime', 'expires', 'includes_tax',
-                  'answers',)
+                  'answers', 'seat')


 class CartPositionCreateSerializer(I18nAwareModelSerializer):
    answers = AnswerCreateSerializer(many=True, required=False)
    expires = serializers.DateTimeField(required=False)
    attendee_name = serializers.CharField(required=False, allow_null=True)
+    seat = serializers.CharField(required=False, allow_null=True)

    class Meta:
        model = CartPosition
        fields = ('cart_id', 'item', 'variation', 'price', 'attendee_name', 'attendee_name_parts', 'attendee_email',
-                  'subevent', 'expires', 'includes_tax', 'answers',)
+                  'subevent', 'expires', 'includes_tax', 'answers', 'seat')

    def create(self, validated_data):
        answers_data = validated_data.pop('answers')
@@ -71,6 +73,22 @@ class CartPositionCreateSerializer(I18nAwareModelSerializer):
                validated_data['attendee_name_parts'] = {
                    '_legacy': attendee_name
                }
+
+            seated = validated_data.get('item').seat_category_mappings.filter(subevent=validated_data.get('subevent')).exists()
+            if validated_data.get('seat'):
+                if not seated:
+                    raise ValidationError('The specified product does not allow to choose a seat.')
+                try:
+                    seat = self.context['event'].seats.get(seat_guid=validated_data['seat'], subevent=validated_data.get('subevent'))
+                except Seat.DoesNotExist:
+                    raise ValidationError('The specified seat does not exist.')
+                else:
+                    validated_data['seat'] = seat
+                    if not seat.is_available():
+                        raise ValidationError(ugettext_lazy('The selected seat "{seat}" is not available.').format(seat=seat.name))
+            elif seated:
+                raise ValidationError('The specified product requires to choose a seat.')
+
            cp = CartPosition.objects.create(event=self.context['event'], **validated_data)

        for answ_data in answers_data:
--- a/src/pretix/api/serializers/event.py
+++ b/src/pretix/api/serializers/event.py
@@ -11,6 +11,9 @@ from pretix.api.serializers.i18n import I18nAwareModelSerializer
 from pretix.base.models import Event, TaxRule
 from pretix.base.models.event import SubEvent
 from pretix.base.models.items import SubEventItem, SubEventItemVariation
+from pretix.base.services.seating import (
+    SeatProtected, generate_seats, validate_plan_change,
+)


 class MetaDataField(Field):
@@ -26,6 +29,22 @@ class MetaDataField(Field):
        }


+class SeatCategoryMappingField(Field):
+
+    def to_representation(self, value):
+        qs = value.seat_category_mappings.all()
+        if isinstance(value, Event):
+            qs = qs.filter(subevent=None)
+        return {
+            v.layout_category: v.product_id for v in qs
+        }
+
+    def to_internal_value(self, data):
+        return {
+            'seat_category_mapping': data or {}
+        }
+
+
 class PluginsField(Field):

    def to_representation(self, obj):
@@ -45,12 +64,14 @@ class PluginsField(Field):
 class EventSerializer(I18nAwareModelSerializer):
    meta_data = MetaDataField(required=False, source='*')
    plugins = PluginsField(required=False, source='*')
+    seat_category_mapping = SeatCategoryMappingField(source='*', required=False)

    class Meta:
        model = Event
        fields = ('name', 'slug', 'live', 'testmode', 'currency', 'date_from',
                  'date_to', 'date_admission', 'is_public', 'presale_start',
-                  'presale_end', 'location', 'has_subevents', 'meta_data', 'plugins')
+                  'presale_end', 'location', 'has_subevents', 'meta_data', 'seating_plan',
+                  'plugins', 'seat_category_mapping')

    def validate(self, data):
        data = super().validate(data)
@@ -61,6 +82,9 @@ class EventSerializer(I18nAwareModelSerializer):
        Event.clean_dates(data.get('date_from'), data.get('date_to'))
        Event.clean_presale(data.get('presale_start'), data.get('presale_end'))

+        if full_data.get('has_subevents') and full_data.get('seating_plan'):
+            raise ValidationError('Event series should not directly be assigned a seating plan.')
+
        return data

    def validate_has_subevents(self, value):
@@ -92,6 +116,27 @@ class EventSerializer(I18nAwareModelSerializer):
                raise ValidationError(_('Meta data property \'{name}\' does not exist.').format(name=key))
        return value

+    def validate_seating_plan(self, value):
+        if value and value.organizer != self.context['request'].organizer:
+            raise ValidationError('Invalid seating plan.')
+        if self.instance and self.instance.pk:
+            try:
+                validate_plan_change(self.instance, None, value)
+            except SeatProtected as e:
+                raise ValidationError(str(e))
+        return value
+
+    def validate_seat_category_mapping(self, value):
+        if value and (not self.instance or not self.instance.pk):
+            raise ValidationError('You cannot specify seat category mappings on event creation.')
+        item_cache = {i.pk: i for i in self.instance.items.all()}
+        result = {}
+        for k, item in value['seat_category_mapping'].items():
+            if item not in item_cache:
+                raise ValidationError('Item \'{id}\' does not exist.'.format(id=item))
+            result[k] = item_cache[item]
+        return {'seat_category_mapping': result}
+
    def validate_plugins(self, value):
        from pretix.base.plugins import get_all_plugins

@@ -109,6 +154,7 @@ class EventSerializer(I18nAwareModelSerializer):
    @transaction.atomic
    def create(self, validated_data):
        meta_data = validated_data.pop('meta_data', None)
+        validated_data.pop('seat_category_mapping', None)
        plugins = validated_data.pop('plugins', settings.PRETIX_PLUGINS_DEFAULT.split(','))
        event = super().create(validated_data)

@@ -120,6 +166,10 @@ class EventSerializer(I18nAwareModelSerializer):
                    value=value
                )

+        # Seats
+        if event.seating_plan:
+            generate_seats(event, None, event.seating_plan, {})
+
        # Plugins
        if plugins is not None:
            event.set_active_plugins(plugins)
@@ -131,6 +181,7 @@ class EventSerializer(I18nAwareModelSerializer):
    def update(self, instance, validated_data):
        meta_data = validated_data.pop('meta_data', None)
        plugins = validated_data.pop('plugins', None)
+        seat_category_mapping = validated_data.pop('seat_category_mapping', None)
        event = super().update(instance, validated_data)

        # Meta data
@@ -151,6 +202,29 @@ class EventSerializer(I18nAwareModelSerializer):
                if prop.name not in meta_data:
                    current_object.delete()

+        # Seats
+        if seat_category_mapping is not None or ('seating_plan' in validated_data and validated_data['seating_plan'] is None):
+            current_mappings = {
+                m.layout_category: m
+                for m in event.seat_category_mappings.filter(subevent=None)
+            }
+            if not event.seating_plan:
+                seat_category_mapping = {}
+            for key, value in seat_category_mapping.items():
+                if key in current_mappings:
+                    m = current_mappings.pop(key)
+                    m.product = value
+                    m.save()
+                else:
+                    event.seat_category_mappings.create(product=value, layout_category=key)
+            for m in current_mappings.values():
+                m.delete()
+        if 'seating_plan' in validated_data or seat_category_mapping is not None:
+            generate_seats(event, None, event.seating_plan, {
+                m.layout_category: m.product
+                for m in event.seat_category_mappings.select_related('product').filter(subevent=None)
+            })
+
        # Plugins
        if plugins is not None:
            event.set_active_plugins(plugins)
@@ -196,14 +270,15 @@ class SubEventItemVariationSerializer(I18nAwareModelSerializer):
 class SubEventSerializer(I18nAwareModelSerializer):
    item_price_overrides = SubEventItemSerializer(source='subeventitem_set', many=True, required=False)
    variation_price_overrides = SubEventItemVariationSerializer(source='subeventitemvariation_set', many=True, required=False)
+    seat_category_mapping = SeatCategoryMappingField(source='*', required=False)
    event = SlugRelatedField(slug_field='slug', read_only=True)
    meta_data = MetaDataField(source='*')

    class Meta:
        model = SubEvent
        fields = ('id', 'name', 'date_from', 'date_to', 'active', 'date_admission',
-                  'presale_start', 'presale_end', 'location', 'event', 'is_public',
-                  'item_price_overrides', 'variation_price_overrides', 'meta_data')
+                  'presale_start', 'presale_end', 'location', 'event', 'is_public', 'seating_plan',
+                  'item_price_overrides', 'variation_price_overrides', 'meta_data', 'seat_category_mapping')

    def validate(self, data):
        data = super().validate(data)
@@ -225,6 +300,25 @@ class SubEventSerializer(I18nAwareModelSerializer):
    def validate_variation_price_overrides(self, data):
        return list(filter(lambda i: 'variation' in i, data))

+    def validate_seating_plan(self, value):
+        if value and value.organizer != self.context['request'].organizer:
+            raise ValidationError('Invalid seating plan.')
+        if self.instance and self.instance.pk:
+            try:
+                validate_plan_change(self.context['request'].event, self.instance, value)
+            except SeatProtected as e:
+                raise ValidationError(str(e))
+        return value
+
+    def validate_seat_category_mapping(self, value):
+        item_cache = {i.pk: i for i in self.context['request'].event.items.all()}
+        result = {}
+        for k, item in value['seat_category_mapping'].items():
+            if item not in item_cache:
+                raise ValidationError('Item \'{id}\' does not exist.'.format(id=item))
+            result[k] = item_cache[item]
+        return {'seat_category_mapping': result}
+
    @cached_property
    def meta_properties(self):
        return {
@@ -242,6 +336,7 @@ class SubEventSerializer(I18nAwareModelSerializer):
        item_price_overrides_data = validated_data.pop('subeventitem_set') if 'subeventitem_set' in validated_data else {}
        variation_price_overrides_data = validated_data.pop('subeventitemvariation_set') if 'subeventitemvariation_set' in validated_data else {}
        meta_data = validated_data.pop('meta_data', None)
+        seat_category_mapping = validated_data.pop('seat_category_mapping', None)
        subevent = super().create(validated_data)

        for item_price_override_data in item_price_overrides_data:
@@ -257,6 +352,18 @@ class SubEventSerializer(I18nAwareModelSerializer):
                    value=value
                )

+        # Seats
+        if subevent.seating_plan:
+            if seat_category_mapping is not None:
+                for key, value in seat_category_mapping.items():
+                    self.context['request'].event.seat_category_mappings.create(
+                        product=value, layout_category=key, subevent=subevent
+                    )
+            generate_seats(self.context['request'].event, subevent, subevent.seating_plan, {
+                m.layout_category: m.product
+                for m in self.context['request'].event.seat_category_mappings.select_related('product').filter(subevent=subevent)
+            })
+
        return subevent

    @transaction.atomic
@@ -264,6 +371,7 @@ class SubEventSerializer(I18nAwareModelSerializer):
        item_price_overrides_data = validated_data.pop('subeventitem_set') if 'subeventitem_set' in validated_data else {}
        variation_price_overrides_data = validated_data.pop('subeventitemvariation_set') if 'subeventitemvariation_set' in validated_data else {}
        meta_data = validated_data.pop('meta_data', None)
+        seat_category_mapping = validated_data.pop('seat_category_mapping', None)
        subevent = super().update(instance, validated_data)

        existing_item_overrides = {item.item: item.id for item in SubEventItem.objects.filter(subevent=subevent)}
@@ -300,6 +408,31 @@ class SubEventSerializer(I18nAwareModelSerializer):
                if prop.name not in meta_data:
                    current_object.delete()

+        # Seats
+        if seat_category_mapping is not None or ('seating_plan' in validated_data and validated_data['seating_plan'] is None):
+            current_mappings = {
+                m.layout_category: m
+                for m in self.context['request'].event.seat_category_mappings.filter(subevent=subevent)
+            }
+            if not subevent.seating_plan:
+                seat_category_mapping = {}
+            for key, value in seat_category_mapping.items():
+                if key in current_mappings:
+                    m = current_mappings.pop(key)
+                    m.product = value
+                    m.save()
+                else:
+                    self.context['request'].event.seat_category_mappings.create(
+                        product=value, layout_category=key, subevent=subevent
+                    )
+            for m in current_mappings.values():
+                m.delete()
+        if 'seating_plan' in validated_data or seat_category_mapping is not None:
+            generate_seats(self.context['request'].event, subevent, subevent.seating_plan, {
+                m.layout_category: m.product
+                for m in self.context['request'].event.seat_category_mappings.select_related('product').filter(subevent=subevent)
+            })
+
        return subevent


--- a/src/pretix/api/serializers/order.py
+++ b/src/pretix/api/serializers/order.py
@@ -1,5 +1,4 @@
 import json
-from collections import Counter
 from decimal import Decimal

 from django.utils.timezone import now
@@ -15,7 +14,7 @@ from pretix.base.channels import get_all_sales_channels
 from pretix.base.i18n import language
 from pretix.base.models import (
    Checkin, Invoice, InvoiceAddress, InvoiceLine, Item, ItemVariation, Order,
-    OrderPosition, Question, QuestionAnswer, SubEvent,
+    OrderPosition, Question, QuestionAnswer, Seat, SubEvent,
 )
 from pretix.base.models.orders import (
    CartPosition, OrderFee, OrderPayment, OrderRefund,
@@ -71,6 +70,13 @@ class AnswerQuestionOptionsIdentifierField(serializers.Field):
        return [o.identifier for o in instance.options.all()]


+class InlineSeatSerializer(I18nAwareModelSerializer):
+
+    class Meta:
+        model = Seat
+        fields = ('id', 'name', 'seat_guid')
+
+
 class AnswerSerializer(I18nAwareModelSerializer):
    question_identifier = AnswerQuestionIdentifierField(source='*', read_only=True)
    option_identifiers = AnswerQuestionOptionsIdentifierField(source='*', read_only=True)
@@ -166,12 +172,13 @@ class OrderPositionSerializer(I18nAwareModelSerializer):
    downloads = PositionDownloadsField(source='*')
    order = serializers.SlugRelatedField(slug_field='code', read_only=True)
    pdf_data = PdfDataSerializer(source='*')
+    seat = InlineSeatSerializer(read_only=True)

    class Meta:
        model = OrderPosition
        fields = ('id', 'order', 'positionid', 'item', 'variation', 'price', 'attendee_name', 'attendee_name_parts',
                  'attendee_email', 'voucher', 'tax_rate', 'tax_value', 'secret', 'addon_to', 'subevent', 'checkins',
-                  'downloads', 'answers', 'tax_rule', 'pseudonymization_id', 'pdf_data')
+                  'downloads', 'answers', 'tax_rule', 'pseudonymization_id', 'pdf_data', 'seat')

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
@@ -430,11 +437,12 @@ class OrderPositionCreateSerializer(I18nAwareModelSerializer):
    addon_to = serializers.IntegerField(required=False, allow_null=True)
    secret = serializers.CharField(required=False)
    attendee_name = serializers.CharField(required=False, allow_null=True)
+    seat = serializers.CharField(required=False, allow_null=True)

    class Meta:
        model = OrderPosition
        fields = ('positionid', 'item', 'variation', 'price', 'attendee_name', 'attendee_name_parts', 'attendee_email',
-                  'secret', 'addon_to', 'subevent', 'answers')
+                  'secret', 'addon_to', 'subevent', 'answers', 'seat')

    def validate_secret(self, secret):
        if secret and OrderPosition.all.filter(order__event=self.context['event'], secret=secret).exists():
@@ -615,8 +623,8 @@ class OrderCreateSerializer(I18nAwareModelSerializer):
            ia = None

        with self.context['event'].lock() as now_dt:
-            quotadiff = Counter()
-
+            free_seats = set()
+            seats_seen = set()
            consume_carts = validated_data.pop('consume_carts', [])
            delete_cps = []
            quota_avail_cache = {}
@@ -630,7 +638,8 @@ class OrderCreateSerializer(I18nAwareModelSerializer):
                        if quota_avail_cache[quota][1] is not None:
                            quota_avail_cache[quota][1] += 1
                    if cp.expires > now_dt:
-                        quotadiff.subtract(quotas)
+                        if cp.seat:
+                            free_seats.add(cp.seat)
                    delete_cps.append(cp)

            errs = [{} for p in positions_data]
@@ -658,7 +667,22 @@ class OrderCreateSerializer(I18nAwareModelSerializer):
                                        )
                                    ]

-                    quotadiff.update(new_quotas)
+            for i, pos_data in enumerate(positions_data):
+                seated = pos_data.get('item').seat_category_mappings.filter(subevent=pos_data.get('subevent')).exists()
+                if pos_data.get('seat'):
+                    if not seated:
+                        errs[i]['seat'] = ['The specified product does not allow to choose a seat.']
+                    try:
+                        seat = self.context['event'].seats.get(seat_guid=pos_data['seat'], subevent=pos_data.get('subevent'))
+                    except Seat.DoesNotExist:
+                        errs[i]['seat'] = ['The specified seat does not exist.']
+                    else:
+                        pos_data['seat'] = seat
+                        if (seat not in free_seats and not seat.is_available()) or seat in seats_seen:
+                            errs[i]['seat'] = [ugettext_lazy('The selected seat "{seat}" is not available.').format(seat=seat.name)]
+                        seats_seen.add(seat)
+                elif seated:
+                    errs[i]['seat'] = ['The specified product requires to choose a seat.']

            if any(errs):
                raise ValidationError({'positions': errs})
--- a/src/pretix/api/serializers/organizer.py
+++ b/src/pretix/api/serializers/organizer.py
@@ -1,8 +1,20 @@
 from pretix.api.serializers.i18n import I18nAwareModelSerializer
-from pretix.base.models import Organizer
+from pretix.api.serializers.order import CompatibleJSONField
+from pretix.base.models import Organizer, SeatingPlan
+from pretix.base.models.seating import SeatingPlanLayoutValidator


 class OrganizerSerializer(I18nAwareModelSerializer):
    class Meta:
        model = Organizer
        fields = ('name', 'slug')
+
+
+class SeatingPlanSerializer(I18nAwareModelSerializer):
+    layout = CompatibleJSONField(
+        validators=[SeatingPlanLayoutValidator()]
+    )
+
+    class Meta:
+        model = SeatingPlan
+        fields = ('id', 'name', 'layout')
--- a/src/pretix/api/urls.py
+++ b/src/pretix/api/urls.py
@@ -18,6 +18,7 @@ orga_router = routers.DefaultRouter()
 orga_router.register(r'events', event.EventViewSet)
 orga_router.register(r'subevents', event.SubEventViewSet)
 orga_router.register(r'webhooks', webhooks.WebHookViewSet)
+orga_router.register(r'seatingplans', organizer.SeatingPlanViewSet)

 event_router = routers.DefaultRouter()
 event_router.register(r'subevents', event.SubEventViewSet)
--- a/src/pretix/api/views/cart.py
+++ b/src/pretix/api/views/cart.py
@@ -24,7 +24,7 @@ class CartPositionViewSet(CreateModelMixin, DestroyModelMixin, viewsets.ReadOnly
        return CartPosition.objects.filter(
            event=self.request.event,
            cart_id__endswith="@api"
-        )
+        ).select_related('seat').prefetch_related('answers')

    def get_serializer_context(self):
        ctx = super().get_serializer_context()
--- a/src/pretix/api/views/checkin.py
+++ b/src/pretix/api/views/checkin.py
@@ -231,7 +231,7 @@ class CheckinListPositionViewSet(viewsets.ReadOnlyModelViewSet):
                    )
                ))
            ).select_related(
-                'item', 'variation', 'item__category', 'addon_to', 'order', 'order__invoice_address'
+                'item', 'variation', 'item__category', 'addon_to', 'order', 'order__invoice_address', 'seat'
            )
        else:
            qs = qs.prefetch_related(
@@ -241,7 +241,7 @@ class CheckinListPositionViewSet(viewsets.ReadOnlyModelViewSet):
                ),
                'answers', 'answers__options', 'answers__question',
                Prefetch('addons', OrderPosition.objects.select_related('item', 'variation'))
-            ).select_related('item', 'variation', 'order', 'addon_to', 'order__invoice_address', 'order')
+            ).select_related('item', 'variation', 'order', 'addon_to', 'order__invoice_address', 'order', 'seat')

        if not self.checkinlist.all_products:
            qs = qs.filter(item__in=self.checkinlist.limit_products.values_list('id', flat=True))
--- a/src/pretix/api/views/event.py
+++ b/src/pretix/api/views/event.py
@@ -86,7 +86,7 @@ class EventViewSet(viewsets.ModelViewSet):
            )

        return qs.prefetch_related(
-            'meta_values', 'meta_values__property'
+            'meta_values', 'meta_values__property', 'seat_category_mappings'
        )

    def perform_update(self, serializer):
@@ -242,7 +242,7 @@ class SubEventViewSet(ConditionalListView, viewsets.ModelViewSet):
                event__in=self.request.user.get_events_with_any_permission()
            )
        return qs.prefetch_related(
-            'subeventitem_set', 'subeventitemvariation_set'
+            'subeventitem_set', 'subeventitemvariation_set', 'seat_category_mappings'
        )

    def perform_update(self, serializer):
--- a/src/pretix/api/views/order.py
+++ b/src/pretix/api/views/order.py
@@ -93,8 +93,8 @@ class OrderViewSet(viewsets.ModelViewSet):
                    'positions',
                    OrderPosition.objects.all().prefetch_related(
                        'checkins', 'item', 'variation', 'answers', 'answers__options', 'answers__question',
-                        'item__category', 'addon_to',
-                        Prefetch('addons', OrderPosition.objects.select_related('item', 'variation'))
+                        'item__category', 'addon_to', 'seat',
+                        Prefetch('addons', OrderPosition.objects.select_related('item', 'variation', 'seat'))
                    )
                )
            )
@@ -103,7 +103,7 @@ class OrderViewSet(viewsets.ModelViewSet):
                Prefetch(
                    'positions',
                    OrderPosition.objects.all().prefetch_related(
-                        'checkins', 'item', 'variation', 'answers', 'answers__options', 'answers__question',
+                        'checkins', 'item', 'variation', 'answers', 'answers__options', 'answers__question', 'seat',
                    )
                )
            )
@@ -611,13 +611,13 @@ class OrderPositionViewSet(mixins.DestroyModelMixin, viewsets.ReadOnlyModelViewS
                    )
                ))
            ).select_related(
-                'item', 'variation', 'item__category', 'addon_to'
+                'item', 'variation', 'item__category', 'addon_to', 'seat'
            )
        else:
            qs = qs.prefetch_related(
                'checkins', 'answers', 'answers__options', 'answers__question'
            ).select_related(
-                'item', 'order', 'order__event', 'order__event__organizer'
+                'item', 'order', 'order__event', 'order__event__organizer', 'seat'
            )
        return qs

--- a/src/pretix/api/views/organizer.py
+++ b/src/pretix/api/views/organizer.py
@@ -1,8 +1,12 @@
 from rest_framework import filters, viewsets
+from rest_framework.exceptions import PermissionDenied

 from pretix.api.models import OAuthAccessToken
-from pretix.api.serializers.organizer import OrganizerSerializer
-from pretix.base.models import Organizer
+from pretix.api.serializers.organizer import (
+    OrganizerSerializer, SeatingPlanSerializer,
+)
+from pretix.base.models import Organizer, SeatingPlan
+from pretix.helpers.dicts import merge_dicts


 class OrganizerViewSet(viewsets.ReadOnlyModelViewSet):
@@ -30,3 +34,50 @@ class OrganizerViewSet(viewsets.ReadOnlyModelViewSet):
            return Organizer.objects.filter(pk=self.request.auth.organizer_id)
        else:
            return Organizer.objects.filter(pk=self.request.auth.team.organizer_id)
+
+
+class SeatingPlanViewSet(viewsets.ModelViewSet):
+    serializer_class = SeatingPlanSerializer
+    queryset = SeatingPlan.objects.none()
+    permission = 'can_change_organizer_settings'
+    write_permission = 'can_change_organizer_settings'
+
+    def get_queryset(self):
+        return self.request.organizer.seating_plans.all()
+
+    def get_serializer_context(self):
+        ctx = super().get_serializer_context()
+        ctx['organizer'] = self.request.organizer
+        return ctx
+
+    def perform_create(self, serializer):
+        inst = serializer.save(organizer=self.request.organizer)
+        self.request.organizer.log_action(
+            'pretix.seatingplan.added',
+            user=self.request.user,
+            auth=self.request.auth,
+            data=merge_dicts(self.request.data, {'id': inst.pk})
+        )
+
+    def perform_update(self, serializer):
+        if serializer.instance.events.exists() or serializer.instance.subevents.exists():
+            raise PermissionDenied('This plan can not be changed while it is in use for an event.')
+        inst = serializer.save(organizer=self.request.organizer)
+        self.request.organizer.log_action(
+            'pretix.seatingplan.changed',
+            user=self.request.user,
+            auth=self.request.auth,
+            data=merge_dicts(self.request.data, {'id': serializer.instance.pk})
+        )
+        return inst
+
+    def perform_destroy(self, instance):
+        if instance.events.exists() or instance.subevents.exists():
+            raise PermissionDenied('This plan can not be deleted while it is in use for an event.')
+        instance.log_action(
+            'pretix.seatingplan.deleted',
+            user=self.request.user,
+            auth=self.request.auth,
+            data={'id': instance.pk}
+        )
+        instance.delete()
--- a/src/pretix/base/migrations/0123_auto_20190530_1035.py
+++ b/src/pretix/base/migrations/0123_auto_20190530_1035.py
@@ -0,0 +1,70 @@
+# Generated by Django 2.2.1 on 2019-05-30 10:35
+
+import django.db.models.deletion
+from django.db import migrations, models
+
+import pretix.base.models.base
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('pretixbase', '0122_orderposition_web_secret'),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='SeatingPlan',
+            fields=[
+                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False)),
+                ('name', models.CharField(max_length=190)),
+                ('layout', models.TextField()),
+                ('organizer', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name='seating_plans', to='pretixbase.Organizer')),
+            ],
+            options={
+                'abstract': False,
+            },
+            bases=(models.Model, pretix.base.models.base.LoggingMixin),
+        ),
+        migrations.CreateModel(
+            name='SeatCategoryMapping',
+            fields=[
+                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False)),
+                ('layout_category', models.CharField(max_length=190)),
+                ('event', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name='seat_category_mappings', to='pretixbase.Event')),
+                ('product', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name='seat_category_mappings', to='pretixbase.Item')),
+                ('subevent', models.ForeignKey(null=True, on_delete=django.db.models.deletion.CASCADE, related_name='seat_category_mappings', to='pretixbase.SubEvent')),
+            ],
+        ),
+        migrations.CreateModel(
+            name='Seat',
+            fields=[
+                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False)),
+                ('name', models.CharField(max_length=190)),
+                ('blocked', models.BooleanField(default=False)),
+                ('event', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name='seats', to='pretixbase.Event')),
+                ('product', models.ForeignKey(null=True, on_delete=django.db.models.deletion.CASCADE, related_name='seats', to='pretixbase.Item')),
+                ('subevent', models.ForeignKey(null=True, on_delete=django.db.models.deletion.CASCADE, related_name='seats', to='pretixbase.SubEvent')),
+            ],
+        ),
+        migrations.AddField(
+            model_name='cartposition',
+            name='seat',
+            field=models.ForeignKey(null=True, on_delete=django.db.models.deletion.PROTECT, to='pretixbase.Seat'),
+        ),
+        migrations.AddField(
+            model_name='event',
+            name='seating_plan',
+            field=models.ForeignKey(null=True, on_delete=django.db.models.deletion.PROTECT, related_name='events', to='pretixbase.SeatingPlan'),
+        ),
+        migrations.AddField(
+            model_name='orderposition',
+            name='seat',
+            field=models.ForeignKey(null=True, on_delete=django.db.models.deletion.PROTECT, to='pretixbase.Seat'),
+        ),
+        migrations.AddField(
+            model_name='subevent',
+            name='seating_plan',
+            field=models.ForeignKey(null=True, on_delete=django.db.models.deletion.PROTECT, related_name='subevents', to='pretixbase.SeatingPlan'),
+        ),
+    ]
--- a/src/pretix/base/migrations/0124_seat_seat_guid.py
+++ b/src/pretix/base/migrations/0124_seat_seat_guid.py
@@ -0,0 +1,19 @@
+# Generated by Django 2.2.1 on 2019-05-30 11:10
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('pretixbase', '0123_auto_20190530_1035'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='seat',
+            name='seat_guid',
+            field=models.CharField(db_index=True, default=None, max_length=190),
+            preserve_default=False,
+        ),
+    ]
--- a/src/pretix/base/models/init.py
+++ b/src/pretix/base/models/init.py
@@ -24,6 +24,7 @@ from .orders import (
 from .organizer import (
    Organizer, Organizer_SettingsStore, Team, TeamAPIToken, TeamInvite,
 )
+from .seating import Seat, SeatCategoryMapping, SeatingPlan
 from .tax import TaxRule
 from .vouchers import Voucher
 from .waitinglist import WaitingListEntry
--- a/src/pretix/base/models/event.py
+++ b/src/pretix/base/models/event.py
@@ -336,6 +336,8 @@ class Event(EventMixin, LoggedModel):
        verbose_name=_('Event series'),
        default=False
    )
+    seating_plan = models.ForeignKey('SeatingPlan', on_delete=models.PROTECT, null=True, blank=True,
+                                     related_name='events')

    objects = ScopedManager(organizer='organizer')

@@ -348,6 +350,26 @@ class Event(EventMixin, LoggedModel):
    def __str__(self):
        return str(self.name)

+    @property
+    def free_seats(self):
+        from .orders import CartPosition, Order, OrderPosition
+        return self.seats.annotate(
+            has_order=Exists(
+                OrderPosition.objects.filter(
+                    order__event=self,
+                    seat_id=OuterRef('pk'),
+                    order__status__in=[Order.STATUS_PENDING, Order.STATUS_PAID]
+                )
+            ),
+            has_cart=Exists(
+                CartPosition.objects.filter(
+                    event=self,
+                    seat_id=OuterRef('pk'),
+                    expires__gte=now()
+                )
+            )
+        ).filter(has_order=False, has_cart=False, blocked=False)
+
    @property
    def presale_has_ended(self):
        if self.has_subevents:
@@ -531,6 +553,24 @@ class Event(EventMixin, LoggedModel):
            for i in items:
                cl.limit_products.add(item_map[i.pk])

+        if other.seating_plan:
+            if other.seating_plan.organizer_id == self.organizer_id:
+                self.seating_plan = other.seating_plan
+            else:
+                self.organizer.seating_plans.create(name=other.seating_plan.name, layout=other.seating_plan.layout)
+            self.save()
+
+        for m in other.seat_category_mappings.filter(subevent__isnull=True):
+            m.pk = None
+            m.event = self
+            m.product = item_map[m.product_id]
+            m.save()
+
+        for s in other.seats.filter(subevent__isnull=True):
+            s.pk = None
+            s.event = self
+            s.save()
+
        for s in other.settings._objects.all():
            s.object = self
            s.pk = None
@@ -874,6 +914,8 @@ class SubEvent(EventMixin, LoggedModel):
        null=True, blank=True,
        verbose_name=_("Frontpage text")
    )
+    seating_plan = models.ForeignKey('SeatingPlan', on_delete=models.PROTECT, null=True, blank=True,
+                                     related_name='subevents')

    items = models.ManyToManyField('Item', through='SubEventItem')
    variations = models.ManyToManyField('ItemVariation', through='SubEventItemVariation')
@@ -888,6 +930,28 @@ class SubEvent(EventMixin, LoggedModel):
    def __str__(self):
        return '{} - {}'.format(self.name, self.get_date_range_display())

+    @property
+    def free_seats(self):
+        from .orders import CartPosition, Order, OrderPosition
+        return self.seats.annotate(
+            has_order=Exists(
+                OrderPosition.objects.filter(
+                    order__event_id=self.event_id,
+                    subevent=self,
+                    seat_id=OuterRef('pk'),
+                    order__status__in=[Order.STATUS_PENDING, Order.STATUS_PAID]
+                )
+            ),
+            has_cart=Exists(
+                CartPosition.objects.filter(
+                    event_id=self.event_id,
+                    subevent=self,
+                    seat_id=OuterRef('pk'),
+                    expires__gte=now()
+                )
+            )
+        ).filter(has_order=False, has_cart=False, blocked=False)
+
    @cached_property
    def settings(self):
        return self.event.settings
--- a/src/pretix/base/models/orders.py
+++ b/src/pretix/base/models/orders.py
@@ -630,7 +630,7 @@ class Order(LockModel, LoggedModel):
            ), tz)
        return term_last

-    def _can_be_paid(self, count_waitinglist=True, ignore_date=False) -> Union[bool, str]:
+    def _can_be_paid(self, count_waitinglist=True, ignore_date=False, force=False) -> Union[bool, str]:
        error_messages = {
            'late_lastdate': _("The payment can not be accepted as the last date of payments configured in the "
                               "payment settings is over."),
@@ -638,29 +638,37 @@ class Order(LockModel, LoggedModel):
                      "payments should be accepted in the payment settings."),
            'require_approval': _('This order is not yet approved by the event organizer.')
        }
-        if self.require_approval:
-            return error_messages['require_approval']
-        term_last = self.payment_term_last
-        if term_last and not ignore_date:
-            if now() > term_last:
-                return error_messages['late_lastdate']
+        if not force:
+            if self.require_approval:
+                return error_messages['require_approval']
+            term_last = self.payment_term_last
+            if term_last and not ignore_date:
+                if now() > term_last:
+                    return error_messages['late_lastdate']

        if self.status == self.STATUS_PENDING:
            return True
-        if not self.event.settings.get('payment_term_accept_late') and not ignore_date:
+        if not self.event.settings.get('payment_term_accept_late') and not ignore_date and not force:
            return error_messages['late']

-        return self._is_still_available(count_waitinglist=count_waitinglist)
+        return self._is_still_available(count_waitinglist=count_waitinglist, force=force)

-    def _is_still_available(self, now_dt: datetime=None, count_waitinglist=True) -> Union[bool, str]:
+    def _is_still_available(self, now_dt: datetime=None, count_waitinglist=True, force=False) -> Union[bool, str]:
        error_messages = {
            'unavailable': _('The ordered product "{item}" is no longer available.'),
+            'seat_unavailable': _('The seat "{seat}" is no longer available.'),
        }
        now_dt = now_dt or now()
-        positions = self.positions.all().select_related('item', 'variation')
+        positions = self.positions.all().select_related('item', 'variation', 'seat')
        quota_cache = {}
        try:
            for i, op in enumerate(positions):
+                if op.seat:
+                    if not op.seat.is_available(ignore_orderpos=op):
+                        raise Quota.QuotaExceededException(error_messages['seat_unavailable'].format(seat=op.seat))
+                if force:
+                    continue
+
                quotas = list(op.quotas)
                if len(quotas) == 0:
                    raise Quota.QuotaExceededException(error_messages['unavailable'].format(
@@ -938,6 +946,8 @@ class AbstractPosition(models.Model):
    :type voucher: Voucher
    :param meta_info: Additional meta information on the position, JSON-encoded.
    :type meta_info: str
+    :param seat: Seat, if reserved seating is used.
+    :type seat: Seat
    """
    subevent = models.ForeignKey(
        SubEvent,
@@ -984,6 +994,9 @@ class AbstractPosition(models.Model):
        verbose_name=_("Meta information"),
        null=True, blank=True
    )
+    seat = models.ForeignKey(
+        'Seat', null=True, blank=True, on_delete=models.PROTECT
+    )

    class Meta:
        abstract = True
@@ -1183,8 +1196,8 @@ class OrderPayment(models.Model):

    def _mark_paid(self, force, count_waitinglist, user, auth, ignore_date=False, overpaid=False):
        from pretix.base.signals import order_paid
-        can_be_paid = self.order._can_be_paid(count_waitinglist=count_waitinglist, ignore_date=ignore_date)
-        if not force and can_be_paid is not True:
+        can_be_paid = self.order._can_be_paid(count_waitinglist=count_waitinglist, ignore_date=ignore_date, force=force)
+        if can_be_paid is not True:
            self.order.log_action('pretix.event.order.quotaexceeded', {
                'message': can_be_paid
            }, user=user, auth=auth)
--- a/src/pretix/base/models/seating.py
+++ b/src/pretix/base/models/seating.py
@@ -0,0 +1,111 @@
+import json
+from collections import namedtuple
+
+import jsonschema
+from django.contrib.staticfiles import finders
+from django.core.exceptions import ValidationError
+from django.db import models
+from django.utils.deconstruct import deconstructible
+from django.utils.timezone import now
+from django.utils.translation import ugettext_lazy as _
+
+from pretix.base.models import Event, Item, LoggedModel, Organizer, SubEvent
+
+
+@deconstructible
+class SeatingPlanLayoutValidator:
+    def __call__(self, value):
+        if not isinstance(value, dict):
+            try:
+                val = json.loads(value)
+            except ValueError:
+                raise ValidationError(_('Your layout file is not a valid JSON file.'))
+        else:
+            val = value
+        with open(finders.find('seating/seating-plan.schema.json'), 'r') as f:
+            schema = json.loads(f.read())
+        try:
+            jsonschema.validate(val, schema)
+        except jsonschema.ValidationError as e:
+            raise ValidationError(_('Your layout file is not a valid seating plan. Error message: {}').format(str(e)))
+
+
+class SeatingPlan(LoggedModel):
+    """
+    Represents an abstract seating plan, without relation to any event.
+    """
+    name = models.CharField(max_length=190, verbose_name=_('Name'))
+    organizer = models.ForeignKey(Organizer, related_name='seating_plans', on_delete=models.CASCADE)
+    layout = models.TextField(validators=[SeatingPlanLayoutValidator()])
+
+    Category = namedtuple('Categrory', 'name')
+    RawSeat = namedtuple('Seat', 'name guid number row category')
+
+    def __str__(self):
+        return self.name
+
+    @property
+    def layout_data(self):
+        return json.loads(self.layout)
+
+    @layout_data.setter
+    def layout_data(self, v):
+        self.layout = json.dumps(v)
+
+    def get_categories(self):
+        return [
+            self.Category(name=c['name'])
+            for c in self.layout_data['categories']
+        ]
+
+    def iter_all_seats(self):
+        for z in self.layout_data['zones']:
+            for r in z['rows']:
+                for s in r['seats']:
+                    yield self.RawSeat(
+                        number=s['seat_number'],
+                        guid=s['seat_guid'],
+                        name='{} {}'.format(r['row_number'], s['seat_number']),  # TODO: Zone? Variable scheme?
+                        row=r['row_number'],
+                        category=s['category']
+                    )
+
+
+class SeatCategoryMapping(models.Model):
+    """
+    Input seating plans have abstract "categories", such as "Balcony seat", etc. This model maps them to actual
+    pretix product on a per-(sub)event level.
+    """
+    event = models.ForeignKey(Event, related_name='seat_category_mappings', on_delete=models.CASCADE)
+    subevent = models.ForeignKey(SubEvent, null=True, blank=True, related_name='seat_category_mappings', on_delete=models.CASCADE)
+    layout_category = models.CharField(max_length=190)
+    product = models.ForeignKey(Item, related_name='seat_category_mappings', on_delete=models.CASCADE)
+
+
+class Seat(models.Model):
+    """
+    This model is used to represent every single specific seat within an (sub)event that can be selected. It's mainly
+    used for internal bookkeeping and not to be modified by users directly.
+    """
+    event = models.ForeignKey(Event, related_name='seats', on_delete=models.CASCADE)
+    subevent = models.ForeignKey(SubEvent, null=True, blank=True, related_name='seats', on_delete=models.CASCADE)
+    name = models.CharField(max_length=190)
+    seat_guid = models.CharField(max_length=190, db_index=True)
+    product = models.ForeignKey('Item', null=True, blank=True, related_name='seats', on_delete=models.CASCADE)
+    blocked = models.BooleanField(default=False)
+
+    def __str__(self):
+        return self.name
+
+    def is_available(self, ignore_cart=None, ignore_orderpos=None):
+        from .orders import Order
+
+        if self.blocked:
+            return False
+        opqs = self.orderposition_set.filter(order__status__in=[Order.STATUS_PENDING, Order.STATUS_PAID])
+        cpqs = self.cartposition_set.filter(expires__gte=now())
+        if ignore_cart:
+            cpqs = cpqs.exclude(pk=ignore_cart.pk)
+        if ignore_orderpos:
+            opqs = opqs.exclude(pk=ignore_orderpos.pk)
+        return not opqs.exists() and not cpqs.exists()
--- a/src/pretix/base/models/vouchers.py
+++ b/src/pretix/base/models/vouchers.py
@@ -10,6 +10,8 @@ from django.utils.timezone import now
 from django.utils.translation import pgettext_lazy, ugettext_lazy as _
 from django_scopes import ScopedManager, scopes_disabled

+from pretix.base.models import SeatCategoryMapping
+
 from ..decimal import round_decimal
 from .base import LoggedModel
 from .event import Event, SubEvent
@@ -395,3 +397,11 @@ class Voucher(LoggedModel):
        """

        return Order.objects.filter(all_positions__voucher__in=[self]).distinct()
+
+    def seating_available(self):
+        kwargs = {}
+        if self.subevent:
+            kwargs['subevent'] = self.subevent
+        if self.quota_id:
+            return SeatCategoryMapping.objects.filter(product__quotas__pk=self.quota_id, **kwargs).exists()
+        return self.item.seat_category_mappings.filter(**kwargs).exists()
--- a/src/pretix/base/pdf.py
+++ b/src/pretix/base/pdf.py
@@ -238,6 +238,11 @@ DEFAULT_VARIABLES = OrderedDict((
            "TIME_FORMAT"
        ) if ev.date_admission else ""
    }),
+    ("seat", {
+        "label": _("Seat name"),
+        "editor_sample": _("3, 4-5"),
+        "evaluate": lambda op, order, ev: str(op.seat if op.seat else _('General admission'))
+    }),
 ))


--- a/src/pretix/base/services/cart.py
+++ b/src/pretix/base/services/cart.py
@@ -6,7 +6,7 @@ from typing import List, Optional
 from celery.exceptions import MaxRetriesExceededError
 from django.core.exceptions import ValidationError
 from django.db import DatabaseError, transaction
-from django.db.models import Q
+from django.db.models import Count, Exists, OuterRef, Q
 from django.dispatch import receiver
 from django.utils.timezone import make_aware, now
 from django.utils.translation import pgettext_lazy, ugettext as _
@@ -14,8 +14,8 @@ from django_scopes import scopes_disabled

 from pretix.base.i18n import language
 from pretix.base.models import (
-    CartPosition, Event, InvoiceAddress, Item, ItemBundle, ItemVariation,
-    Voucher,
+    CartPosition, Event, InvoiceAddress, Item, ItemBundle, ItemVariation, Seat,
+    SeatCategoryMapping, Voucher,
 )
 from pretix.base.models.event import SubEvent
 from pretix.base.models.orders import OrderFee
@@ -91,15 +91,20 @@ error_messages = {
                         'product %(base)s.'),
    'addon_only': _('One of the products you selected can only be bought as an add-on to another project.'),
    'bundled_only': _('One of the products you selected can only be bought part of a bundle.'),
+    'seat_required': _('You need to select a specific seat.'),
+    'seat_invalid': _('Please select a valid seat.'),
+    'seat_forbidden': _('You can not select a seat for this position.'),
+    'seat_unavailable': _('The seat you selected has already been taken. Please select a different seat.'),
+    'seat_multiple': _('You can not select the same seat multiple times.'),
 }


 class CartManager:
    AddOperation = namedtuple('AddOperation', ('count', 'item', 'variation', 'price', 'voucher', 'quotas',
-                                               'addon_to', 'subevent', 'includes_tax', 'bundled'))
+                                               'addon_to', 'subevent', 'includes_tax', 'bundled', 'seat'))
    RemoveOperation = namedtuple('RemoveOperation', ('position',))
    ExtendOperation = namedtuple('ExtendOperation', ('position', 'count', 'item', 'variation', 'price', 'voucher',
-                                                     'quotas', 'subevent'))
+                                                     'quotas', 'subevent', 'seat'))
    order = {
        RemoveOperation: 10,
        ExtendOperation: 20,
@@ -117,6 +122,7 @@ class CartManager:
        self._items_cache = {}
        self._subevents_cache = {}
        self._variations_cache = {}
+        self._seated_cache = {}
        self._expiry = None
        self.invoice_address = invoice_address
        self._widget_data = widget_data or {}
@@ -128,6 +134,11 @@ class CartManager:
            Q(cart_id=self.cart_id) & Q(event=self.event)
        ).select_related('item', 'subevent')

+    def _is_seated(self, item, subevent):
+        if (item, subevent) not in self._seated_cache:
+            self._seated_cache[item, subevent] = item.seat_category_mappings.filter(subevent=subevent).exists()
+        return self._seated_cache[item, subevent]
+
    def _calculate_expiry(self):
        self._expiry = self.now_dt + timedelta(minutes=self.event.settings.get('reservation_time', as_type=int))

@@ -188,6 +199,8 @@ class CartManager:
            i.pk: i
            for i in self.event.items.select_related('category').prefetch_related(
                'addons', 'bundles', 'addons__addon_category', 'quotas'
+            ).annotate(
+                has_variations=Count('variations'),
            ).filter(
                id__in=[i for i in item_ids if i and i not in self._items_cache]
            )
@@ -224,6 +237,12 @@ class CartManager:
            if self._sales_channel not in op.item.sales_channels:
                raise CartError(error_messages['unavailable'])

+            if op.item.has_variations and not op.variation:
+                raise CartError(error_messages['not_for_sale'])
+
+            if op.variation and op.variation.item_id != op.item.pk:
+                raise CartError(error_messages['not_for_sale'])
+
            if op.voucher and not op.voucher.applies_to(op.item, op.variation):
                raise CartError(error_messages['voucher_invalid_item'])

@@ -239,6 +258,16 @@ class CartManager:
            if op.subevent and op.subevent.presale_has_ended:
                raise CartError(error_messages['ended'])

+            seated = self._is_seated(op.item, op.subevent)
+            if seated and (not op.seat or op.seat.blocked):
+                raise CartError(error_messages['seat_invalid'])
+            elif op.seat and not seated:
+                raise CartError(error_messages['seat_forbidden'])
+            elif op.seat and op.seat.product != op.item:
+                raise CartError(error_messages['seat_invalid'])
+            elif op.seat and op.count > 1:
+                raise CartError('Invalid request: A seat can only be bought once.')
+
            if op.subevent:
                tlv = self.event.settings.get('payment_term_last', as_type=RelativeDateWrapper)
                if tlv:
@@ -301,6 +330,13 @@ class CartManager:
    def extend_expired_positions(self):
        expired = self.positions.filter(expires__lte=self.now_dt).select_related(
            'item', 'variation', 'voucher', 'addon_to', 'addon_to__item'
+        ).annotate(
+            requires_seat=Exists(
+                SeatCategoryMapping.objects.filter(
+                    Q(product=OuterRef('item'))
+                    & (Q(subevent=OuterRef('subevent')) if self.event.has_subevents else Q(subevent__isnull=True))
+                )
+            )
        ).prefetch_related(
            'item__quotas',
            'variation__quotas',
@@ -313,6 +349,8 @@ class CartManager:
            if cp.pk in removed_positions or (cp.addon_to_id and cp.addon_to_id in removed_positions):
                continue

+            cp.item.requires_seat = cp.requires_seat
+
            if cp.is_bundled:
                try:
                    bundle = cp.addon_to.item.bundles.get(bundled_item=cp.item, bundled_variation=cp.variation)
@@ -359,7 +397,7 @@ class CartManager:

            op = self.ExtendOperation(
                position=cp, item=cp.item, variation=cp.variation, voucher=cp.voucher, count=1,
-                price=price, quotas=quotas, subevent=cp.subevent
+                price=price, quotas=quotas, subevent=cp.subevent, seat=cp.seat
            )
            self._check_item_constraints(op)

@@ -378,12 +416,6 @@ class CartManager:
        operations = []

        for i in items:
-            # Check whether the specified items are part of what we just fetched from the database
-            # If they are not, the user supplied item IDs which either do not exist or belong to
-            # a different event
-            if i['item'] not in self._items_cache or (i['variation'] and i['variation'] not in self._variations_cache):
-                raise CartError(error_messages['not_for_sale'])
-
            if self.event.has_subevents:
                if not i.get('subevent'):
                    raise CartError(error_messages['subevent_required'])
@@ -391,6 +423,24 @@ class CartManager:
            else:
                subevent = None

+            # When a seat is given, we ignore the item that was given, since we can infer it from the
+            # seat. The variation is still relevant, though!
+            seat = None
+            if i.get('seat'):
+                try:
+                    seat = (subevent or self.event).seats.get(seat_guid=i.get('seat'))
+                except Seat.DoesNotExist:
+                    raise CartError(error_messages['seat_invalid'])
+                i['item'] = seat.product_id
+                if i['item'] not in self._items_cache:
+                    self._update_items_cache([i['item']], [i['variation']])
+
+            # Check whether the specified items are part of what we just fetched from the database
+            # If they are not, the user supplied item IDs which either do not exist or belong to
+            # a different event
+            if i['item'] not in self._items_cache or (i['variation'] and i['variation'] not in self._variations_cache):
+                raise CartError(error_messages['not_for_sale'])
+
            item = self._items_cache[i['item']]
            variation = self._variations_cache[i['variation']] if i['variation'] is not None else None
            voucher = None
@@ -446,7 +496,7 @@ class CartManager:
                bop = self.AddOperation(
                    count=bundle.count, item=bitem, variation=bvar, price=bprice,
                    voucher=None, quotas=bundle_quotas, addon_to='FAKE', subevent=subevent,
-                    includes_tax=bool(bprice.rate), bundled=[]
+                    includes_tax=bool(bprice.rate), bundled=[], seat=None
                )
                self._check_item_constraints(bop)
                bundled.append(bop)
@@ -455,7 +505,7 @@ class CartManager:

            op = self.AddOperation(
                count=i['count'], item=item, variation=variation, price=price, voucher=voucher, quotas=quotas,
-                addon_to=False, subevent=subevent, includes_tax=bool(price.rate), bundled=bundled
+                addon_to=False, subevent=subevent, includes_tax=bool(price.rate), bundled=bundled, seat=seat
            )
            self._check_item_constraints(op)
            operations.append(op)
@@ -561,7 +611,7 @@ class CartManager:

                op = self.AddOperation(
                    count=1, item=item, variation=variation, price=price, voucher=None, quotas=quotas,
-                    addon_to=cp, subevent=cp.subevent, includes_tax=bool(price.rate), bundled=[]
+                    addon_to=cp, subevent=cp.subevent, includes_tax=bool(price.rate), bundled=[], seat=cp.seat
                )
                self._check_item_constraints(op)
                operations.append(op)
@@ -687,6 +737,7 @@ class CartManager:
        err = err or self._check_min_per_product()

        self._operations.sort(key=lambda a: self.order[type(a)])
+        seats_seen = set()

        for op in self._operations:
            if isinstance(op, self.RemoveOperation):
@@ -700,6 +751,11 @@ class CartManager:
                # Create a CartPosition for as much items as we can
                requested_count = quota_available_count = voucher_available_count = op.count

+                if op.seat:
+                    if op.seat in seats_seen:
+                        err = err or error_messages['seat_multiple']
+                    seats_seen.add(op.seat)
+
                if op.quotas:
                    quota_available_count = min(requested_count, min(quotas_ok[q] for q in op.quotas))

@@ -745,12 +801,16 @@ class CartManager:
                    available_count = 0

                if isinstance(op, self.AddOperation):
+                    if op.seat and not op.seat.is_available():
+                        available_count = 0
+                        err = err or error_messages['seat_unavailable']
+
                    for k in range(available_count):
                        cp = CartPosition(
                            event=self.event, item=op.item, variation=op.variation,
                            price=op.price.gross, expires=self._expiry, cart_id=self.cart_id,
                            voucher=op.voucher, addon_to=op.addon_to if op.addon_to else None,
-                            subevent=op.subevent, includes_tax=op.includes_tax
+                            subevent=op.subevent, includes_tax=op.includes_tax, seat=op.seat
                        )
                        if self.event.settings.attendee_names_asked:
                            scheme = PERSON_NAME_SCHEMES.get(self.event.settings.name_scheme)
@@ -789,7 +849,11 @@ class CartManager:

                        new_cart_positions.append(cp)
                elif isinstance(op, self.ExtendOperation):
-                    if available_count == 1:
+                    if op.seat and not op.seat.is_available(ignore_cart=op.position):
+                        err = err or error_messages['seat_unavailable']
+                        op.position.addons.all().delete()
+                        op.position.delete()
+                    elif available_count == 1:
                        op.position.expires = self._expiry
                        op.position.price = op.price.gross
                        try:
@@ -820,6 +884,9 @@ class CartManager:
            # If any quotas are affected that are not unlimited, we lock
            return True

+        if any(getattr(o, 'seat', False) for o in self._operations):
+            return True
+
        return False

    def commit(self):
@@ -909,7 +976,7 @@ def add_items_to_cart(self, event: int, items: List[dict], cart_id: str=None, lo
    """
    Adds a list of items to a user's cart.
    :param event: The event ID in question
-    :param items: A list of dicts with the keys item, variation, count, custom_price, voucher
+    :param items: A list of dicts with the keys item, variation, count, custom_price, voucher, seat ID
    :param cart_id: Session ID of a guest
    :raises CartError: On any error that occured
    """
--- a/src/pretix/base/services/orders.py
+++ b/src/pretix/base/services/orders.py
@@ -24,7 +24,7 @@ from pretix.base.i18n import (
 )
 from pretix.base.models import (
    CartPosition, Device, Event, Item, ItemVariation, Order, OrderPayment,
-    OrderPosition, Quota, User, Voucher,
+    OrderPosition, Quota, Seat, SeatCategoryMapping, User, Voucher,
 )
 from pretix.base.models.event import SubEvent
 from pretix.base.models.items import ItemBundle
@@ -82,6 +82,8 @@ error_messages = {
                                   'affected positions have been removed from your cart.'),
    'some_subevent_ended': _('The presale period for one of the events in your cart has ended. The affected '
                             'positions have been removed from your cart.'),
+    'seat_invalid': _('One of the seats in your order was invalid, we removed the position from your cart.'),
+    'seat_unavailable': _('One of the seats in your order has been taken in the meantime, we removed the position from your cart.'),
 }

 logger = logging.getLogger(__name__)
@@ -428,6 +430,7 @@ def _check_positions(event: Event, now_dt: datetime, positions: List[CartPositio
    products_seen = Counter()
    changed_prices = {}
    deleted_positions = set()
+    seats_seen = set()

    def delete(cp):
        # Delete a cart position, including parents and children, if applicable
@@ -490,6 +493,13 @@ def _check_positions(event: Event, now_dt: datetime, positions: List[CartPositio
            delete(cp)
            break

+        if (cp.requires_seat and not cp.seat) or (cp.seat and not cp.requires_seat) or (cp.seat and cp.seat.product != cp.item) or cp.seat in seats_seen:
+            err = err or error_messages['seat_invalid']
+            delete(cp)
+            break
+        if cp.seat:
+            seats_seen.add(cp.seat)
+
        if cp.item.require_voucher and cp.voucher is None:
            delete(cp)
            err = err or error_messages['voucher_required']
@@ -501,6 +511,14 @@ def _check_positions(event: Event, now_dt: datetime, positions: List[CartPositio
            err = error_messages['voucher_required']
            break

+        if cp.seat:
+            # Unlike quotas (which we blindly trust as long as the position is not expired), we check seats every time, since we absolutely
+            # can not overbook a seat.
+            if not cp.seat.is_available(ignore_cart=cp) or cp.seat.blocked:
+                err = err or error_messages['seat_unavailable']
+                cp.delete()
+                continue
+
        if cp.expires >= now_dt and not cp.voucher:
            # Other checks are not necessary
            continue
@@ -736,21 +754,30 @@ def _perform_order(event: Event, payment_provider: str, position_ids: List[str],
        except InvoiceAddress.DoesNotExist:
            pass

-    positions = CartPosition.objects.filter(id__in=position_ids, event=event)
+    positions = CartPosition.objects.annotate(
+        requires_seat=Exists(
+            SeatCategoryMapping.objects.filter(
+                Q(product=OuterRef('item'))
+                & (Q(subevent=OuterRef('subevent')) if event.has_subevents else Q(subevent__isnull=True))
+            )
+        )
+    ).filter(
+        id__in=position_ids, event=event
+    )

    validate_order.send(event, payment_provider=pprov, email=email, positions=positions,
                        locale=locale, invoice_address=addr, meta_info=meta_info)

    lockfn = NoLockManager
    locked = False
-    if positions.filter(Q(voucher__isnull=False) | Q(expires__lt=now() + timedelta(minutes=2))).exists():
+    if positions.filter(Q(voucher__isnull=False) | Q(expires__lt=now() + timedelta(minutes=2)) | Q(seat__isnull=False)).exists():
        # Performance optimization: If no voucher is used and no cart position is dangerously close to its expiry date,
        # creating this order shouldn't be prone to any race conditions and we don't need to lock the event.
        locked = True
        lockfn = event.lock

    with lockfn() as now_dt:
-        positions = list(positions.select_related('item', 'variation', 'subevent', 'addon_to').prefetch_related('addons'))
+        positions = list(positions.select_related('item', 'variation', 'subevent', 'seat', 'addon_to').prefetch_related('addons'))
        if len(positions) == 0:
            raise OrderError(error_messages['empty'])
        if len(position_ids) != len(positions):
@@ -961,12 +988,17 @@ class OrderChangeManager:
        'addon_to_required': _('This is an add-on product, please select the base position it should be added to.'),
        'addon_invalid': _('The selected base position does not allow you to add this product as an add-on.'),
        'subevent_required': _('You need to choose a subevent for the new position.'),
+        'seat_unavailable': _('The selected seat "{seat}" is not available.'),
+        'seat_subevent_mismatch': _('You selected seat "{seat}" for a date that does not match the selected ticket date. Please choose a seat again.'),
+        'seat_required': _('The selected product requires you to select a seat.'),
+        'seat_forbidden': _('The selected product does not allow to select a seat.'),
    }
    ItemOperation = namedtuple('ItemOperation', ('position', 'item', 'variation'))
    SubeventOperation = namedtuple('SubeventOperation', ('position', 'subevent'))
+    SeatOperation = namedtuple('SubeventOperation', ('position', 'seat'))
    PriceOperation = namedtuple('PriceOperation', ('position', 'price'))
    CancelOperation = namedtuple('CancelOperation', ('position',))
-    AddOperation = namedtuple('AddOperation', ('item', 'variation', 'price', 'addon_to', 'subevent'))
+    AddOperation = namedtuple('AddOperation', ('item', 'variation', 'price', 'addon_to', 'subevent', 'seat'))
    SplitOperation = namedtuple('SplitOperation', ('position',))
    RegenerateSecretOperation = namedtuple('RegenerateSecretOperation', ('position',))

@@ -979,6 +1011,7 @@ class OrderChangeManager:
        self._committed = False
        self._totaldiff = 0
        self._quotadiff = Counter()
+        self._seatdiff = Counter()
        self._operations = []
        self.notify = notify
        self._invoice_dirty = False
@@ -996,6 +1029,13 @@ class OrderChangeManager:
        self._quotadiff.subtract(position.quotas)
        self._operations.append(self.ItemOperation(position, item, variation))

+    def change_seat(self, position: OrderPosition, seat: Seat):
+        if position.seat:
+            self._seatdiff.subtract([position.seat])
+        if seat:
+            self._seatdiff.update([seat])
+        self._operations.append(self.SeatOperation(position, seat))
+
    def change_subevent(self, position: OrderPosition, subevent: SubEvent):
        price = get_price(position.item, position.variation, voucher=position.voucher, subevent=subevent,
                          invoice_address=self._invoice_address)
@@ -1051,12 +1091,14 @@ class OrderChangeManager:
        self._totaldiff += -position.price
        self._quotadiff.subtract(position.quotas)
        self._operations.append(self.CancelOperation(position))
+        if position.seat:
+            self._seatdiff.subtract([position.seat])

        if self.order.event.settings.invoice_include_free or position.price != Decimal('0.00'):
            self._invoice_dirty = True

    def add_position(self, item: Item, variation: ItemVariation, price: Decimal, addon_to: Order = None,
-                     subevent: SubEvent = None):
+                     subevent: SubEvent = None, seat: Seat = None):
        if price is None:
            price = get_price(item, variation, subevent=subevent, invoice_address=self._invoice_address)
        else:
@@ -1075,6 +1117,14 @@ class OrderChangeManager:
        if self.order.event.has_subevents and not subevent:
            raise OrderError(self.error_messages['subevent_required'])

+        seated = item.seat_category_mappings.filter(subevent=subevent).exists()
+        if seated and not seat:
+            raise OrderError(self.error_messages['seat_required'])
+        elif not seated and seat:
+            raise OrderError(self.error_messages['seat_forbidden'])
+        if seat and subevent and seat.subevent_id != subevent:
+            raise OrderError(self.error_messages['seat_subevent_mismatch'].format(seat=seat.name))
+
        new_quotas = (variation.quotas.filter(subevent=subevent)
                      if variation else item.quotas.filter(subevent=subevent))
        if not new_quotas:
@@ -1085,7 +1135,9 @@ class OrderChangeManager:

        self._totaldiff += price.gross
        self._quotadiff.update(new_quotas)
-        self._operations.append(self.AddOperation(item, variation, price, addon_to, subevent))
+        if seat:
+            self._seatdiff.update([seat])
+        self._operations.append(self.AddOperation(item, variation, price, addon_to, subevent, seat))

    def split(self, position: OrderPosition):
        if self.order.event.settings.invoice_include_free or position.price != Decimal('0.00'):
@@ -1093,6 +1145,26 @@ class OrderChangeManager:

        self._operations.append(self.SplitOperation(position))

+    def _check_seats(self):
+        for seat, diff in self._seatdiff.items():
+            if diff <= 0:
+                continue
+            if not seat.is_available() or diff > 1:
+                raise OrderError(self.error_messages['seat_unavailable'].format(seat=seat.name))
+
+        if self.event.has_subevents:
+            state = {}
+            for p in self.order.positions.all():
+                state[p] = {'seat': p.seat, 'subevent': p.subevent}
+            for op in self._operations:
+                if isinstance(op, self.SeatOperation):
+                    state[op.position]['seat'] = op.seat
+                elif isinstance(op, self.SubeventOperation):
+                    state[op.position]['subevent'] = op.subevent
+            for v in state.values():
+                if v['seat'] and v['seat'].subevent_id != v['subevent'].pk:
+                    raise OrderError(self.error_messages['seat_subevent_mismatch'].format(seat=v['seat'].name))
+
    def _check_quotas(self):
        for quota, diff in self._quotadiff.items():
            if diff <= 0:
@@ -1179,6 +1251,17 @@ class OrderChangeManager:
                op.position.variation = op.variation
                op.position._calculate_tax()
                op.position.save()
+            elif isinstance(op, self.SeatOperation):
+                self.order.log_action('pretix.event.order.changed.seat', user=self.user, auth=self.auth, data={
+                    'position': op.position.pk,
+                    'positionid': op.position.positionid,
+                    'old_seat': op.position.seat.name if op.position.seat else "-",
+                    'new_seat': op.seat.name if op.seat else "-",
+                    'old_seat_id': op.position.seat.pk if op.position.seat else None,
+                    'new_seat_id': op.seat.pk if op.seat else None,
+                })
+                op.position.seat = op.seat
+                op.position.save()
            elif isinstance(op, self.SubeventOperation):
                self.order.log_action('pretix.event.order.changed.subevent', user=self.user, auth=self.auth, data={
                    'position': op.position.pk,
@@ -1232,7 +1315,7 @@ class OrderChangeManager:
                    item=op.item, variation=op.variation, addon_to=op.addon_to,
                    price=op.price.gross, order=self.order, tax_rate=op.price.rate,
                    tax_value=op.price.tax, tax_rule=op.item.tax_rule,
-                    positionid=nextposid, subevent=op.subevent
+                    positionid=nextposid, subevent=op.subevent, seat=op.seat
                )
                nextposid += 1
                self.order.log_action('pretix.event.order.changed.add', user=self.user, auth=self.auth, data={
@@ -1243,6 +1326,7 @@ class OrderChangeManager:
                    'price': op.price.gross,
                    'positionid': pos.positionid,
                    'subevent': op.subevent.pk if op.subevent else None,
+                    'seat': op.seat.pk if op.seat else None,
                })
            elif isinstance(op, self.SplitOperation):
                split_positions.append(op.position)
@@ -1467,6 +1551,7 @@ class OrderChangeManager:
                    raise OrderError(self.error_messages['not_pending_or_paid'])
                if check_quotas:
                    self._check_quotas()
+                self._check_seats()
                self._check_complete_cancel()
                self._perform_operations()
            self._recalculate_total_and_payment_fee()
--- a/src/pretix/base/services/seating.py
+++ b/src/pretix/base/services/seating.py
@@ -0,0 +1,57 @@
+from django.db.models import Count
+from django.utils.translation import ugettext_lazy as _
+
+from pretix.base.models import CartPosition, Seat
+
+
+class SeatProtected(Exception):
+    pass
+
+
+def validate_plan_change(event, subevent, plan):
+    current_taken_seats = set(
+        event.seats.select_related('product')
+             .annotate(has_op=Count('orderposition'))
+             .filter(subevent=subevent, has_op=True)
+             .values_list('seat_guid', flat=True)
+    )
+    new_seats = {
+        ss.guid for ss in plan.iter_all_seats()
+    } if plan else set()
+    leftovers = list(current_taken_seats - new_seats)
+    if leftovers:
+        raise SeatProtected(_('You can not change the plan since seat "{}" is not present in the new plan and is '
+                              'already sold.').format(leftovers[0]))
+
+
+def generate_seats(event, subevent, plan, mapping):
+    current_seats = {
+        s.seat_guid: s for s in
+        event.seats.select_related('product').annotate(has_op=Count('orderposition')).filter(subevent=subevent)
+    }
+    create_seats = []
+    if plan:
+        for ss in plan.iter_all_seats():
+            p = mapping.get(ss.category)
+            if ss.guid in current_seats:
+                seat = current_seats.pop(ss.guid)
+                if seat.product != p:
+                    seat.product = p
+                    seat.save()
+            else:
+                create_seats.append(Seat(
+                    event=event,
+                    subevent=subevent,
+                    seat_guid=ss.guid,
+                    name=ss.name,
+                    product=p,
+                ))
+
+    for s in current_seats.values():
+        if s.has_op:
+            raise SeatProtected(_('You can not change the plan since seat "{}" is not present in the new plan and is '
+                                  'already sold.').format(s.name))
+
+    Seat.objects.bulk_create(create_seats)
+    CartPosition.objects.filter(seat__in=[s.pk for s in current_seats.values()]).delete()
+    Seat.objects.filter(pk__in=[s.pk for s in current_seats.values()]).delete()
--- a/src/pretix/control/forms/orders.py
+++ b/src/pretix/control/forms/orders.py
@@ -10,7 +10,9 @@ from django.utils.translation import pgettext_lazy, ugettext_lazy as _

 from pretix.base.forms import I18nModelForm, PlaceholderValidator
 from pretix.base.forms.widgets import DatePickerWidget
-from pretix.base.models import InvoiceAddress, ItemAddOn, Order, OrderPosition
+from pretix.base.models import (
+    InvoiceAddress, ItemAddOn, Order, OrderPosition, Seat,
+)
 from pretix.base.models.event import SubEvent
 from pretix.base.services.pricing import get_price
 from pretix.control.forms.widgets import Select2
@@ -196,6 +198,12 @@ class OrderPositionAddForm(forms.Form):
        required=False,
        label=_('Add-on to'),
    )
+    seat = forms.ModelChoiceField(
+        Seat.objects.none(),
+        required=False,
+        label=_('Seat'),
+        empty_label=_('General admission')
+    )
    price = forms.DecimalField(
        required=False,
        max_digits=10, decimal_places=2,
@@ -241,6 +249,19 @@ class OrderPositionAddForm(forms.Form):
        else:
            del self.fields['addon_to']

+        self.fields['seat'].queryset = order.event.seats.all()
+        self.fields['seat'].widget = Select2(
+            attrs={
+                'data-model-select2': 'seat',
+                'data-select2-url': reverse('control:event.seats.select2', kwargs={
+                    'event': order.event.slug,
+                    'organizer': order.event.organizer.slug,
+                }),
+                'data-placeholder': _('General admission')
+            }
+        )
+        self.fields['seat'].widget.choices = self.fields['seat'].choices
+
        if order.event.has_subevents:
            self.fields['subevent'].queryset = order.event.subevents.all()
            self.fields['subevent'].widget = Select2(
@@ -269,6 +290,11 @@ class OrderPositionChangeForm(forms.Form):
        required=False,
        empty_label=_('(Unchanged)')
    )
+    seat = forms.ModelChoiceField(
+        Seat.objects.none(),
+        required=False,
+        empty_label=_('(Unchanged)')
+    )
    price = forms.DecimalField(
        required=False,
        max_digits=10, decimal_places=2,
@@ -312,6 +338,22 @@ class OrderPositionChangeForm(forms.Form):
        else:
            del self.fields['subevent']

+        if instance.seat:
+            self.fields['seat'].queryset = instance.order.event.seats.all()
+            self.fields['seat'].widget = Select2(
+                attrs={
+                    'data-model-select2': 'seat',
+                    'data-select2-url': reverse('control:event.seats.select2', kwargs={
+                        'event': instance.order.event.slug,
+                        'organizer': instance.order.event.organizer.slug,
+                    }),
+                    'data-placeholder': _('(Unchanged)')
+                }
+            )
+            self.fields['seat'].widget.choices = self.fields['seat'].choices
+        else:
+            del self.fields['seat']
+
        choices = [
            ('', _('(Unchanged)'))
        ]
--- a/src/pretix/control/forms/subevents.py
+++ b/src/pretix/control/forms/subevents.py
@@ -36,7 +36,7 @@ class SubEventForm(I18nModelForm):
            'presale_start',
            'presale_end',
            'location',
-            'frontpage_text'
+            'frontpage_text',
        ]
        field_classes = {
            'date_from': SplitDateTimeField,
--- a/src/pretix/control/logdisplay.py
+++ b/src/pretix/control/logdisplay.py
@@ -42,6 +42,12 @@ def _display_order_changed(event: Event, logentry: LogEntry):
            old_price=money_filter(Decimal(data['old_price']), event.currency),
            new_price=money_filter(Decimal(data['new_price']), event.currency),
        )
+    elif logentry.action_type == 'pretix.event.order.changed.seat':
+        return text + ' ' + _('Position #{posid}: Seat "{old_seat}" changed '
+                              'to "{new_seat}".').format(
+            posid=data.get('positionid', '?'),
+            old_seat=data.get('old_seat'), new_seat=data.get('new_seat'),
+        )
    elif logentry.action_type == 'pretix.event.order.changed.subevent':
        old_se = str(event.subevents.get(pk=data['old_subevent']))
        new_se = str(event.subevents.get(pk=data['new_subevent']))
--- a/src/pretix/control/signals.py
+++ b/src/pretix/control/signals.py
@@ -279,6 +279,22 @@ styles. It is advisable to set a prefix for your form to avoid clashes with othe
 As with all plugin signals, the ``sender`` keyword argument will contain the event.
 """

+subevent_forms = EventPluginSignal(
+    providing_args=['request', 'subevent']
+)
+"""
+This signal allows you to return additional forms that should be rendered on the subevent creation
+or modification page. You are passed ``request`` and ``subevent`` arguments and are expected to return
+an instance of a form class that you bind yourself when appropriate. Your form will be executed
+as part of the standard validation and rendering cycle and rendered using default bootstrap
+styles. It is advisable to set a prefix for your form to avoid clashes with other plugins.
+
+``subevent`` can be ``None`` during creation. Before ``save()`` is called, a ``subevent`` property of
+your form instance will automatically being set to the subevent that has just been created.
+
+As with all plugin signals, the ``sender`` keyword argument will contain the event.
+"""
+
 oauth_application_registered = Signal(
    providing_args=["user", "application"]
 )
--- a/src/pretix/control/templates/pretixcontrol/base.html
+++ b/src/pretix/control/templates/pretixcontrol/base.html
@@ -145,7 +145,11 @@
                            <a href="{{ nav.url }}" title="{{ nav.title }}" {% if nav.active %}class="active"{% endif %}
                                    {% if nav.children %}class="dropdown-toggle" data-toggle="dropdown"{% endif %}>
                                {% if nav.icon %}
-                                    <span class="fa fa-{{ nav.icon }}"></span>
+                                    {% if "<svg" in nav.icon %}
+                                        {{ nav.icon|safe }}
+                                    {% else %}
+                                        <span class="fa fa-{{ nav.icon }}"></span>
+                                    {% endif %}
                                    <span class="visible-xs-inline">{{ nav.label }}</span>
                                {% else %}
                                    {{ nav.label }}
@@ -270,7 +274,11 @@
                                        <a href="{{ nav.url }}" {% if nav.active %}class="active"{% endif %}
                                                {% if nav.children %}class="has-children"{% endif %}>
                                            {% if nav.icon %}
-                                                <i class="fa fa-{{ nav.icon }} fa-fw"></i>
+                                                {% if "<svg" in nav.icon %}
+                                                    {{ nav.icon|safe }}
+                                                {% else %}
+                                                    <span class="fa fa-fw fa-{{ nav.icon }}"></span>
+                                                {% endif %}
                                            {% endif %}
                                            {{ nav.label }}
                                        </a>
--- a/src/pretix/control/templates/pretixcontrol/order/change.html
+++ b/src/pretix/control/templates/pretixcontrol/order/change.html
@@ -72,7 +72,7 @@
                    </h3>
                </div>
                <div class="panel-body">
-                    <div class="form-order-change" data-pricecalc-endpoint="{% url "api-v1:orderposition-price_calc" organizer=order.event.organizer.slug event=order.event.slug pk=position.pk %}">
+                    <div class="form-order-change" data-pricecalc-endpoint="{% url "api-v1:orderposition-price_calc" organizer=order.event.organizer.slug event=order.event.slug pk=position.pk %}" {% if position.subevent %}data-subevent="{{ position.subevent.id }}{% endif %}">
                        {% bootstrap_form_errors position.form %}
                        {% if position.custom_error %}
                            <div class="alert alert-danger">
@@ -87,20 +87,6 @@
                                <strong>{% trans "Change to" %}</strong>
                            </div>
                        </div>
-                        <div class="row">
-                            <div class="col-sm-3">
-                                <strong>{% trans "Product" %}</strong>
-                            </div>
-                            <div class="col-sm-5">
-                                {{ position.item }}
-                                {% if position.variation %}
-                                    – {{ position.variation }}
-                                {% endif %}
-                            </div>
-                            <div class="col-sm-4">
-                                {% bootstrap_field position.form.itemvar layout='inline' %}
-                            </div>
-                        </div>

                        {% if request.event.has_subevents %}
                            <div class="row">
@@ -116,6 +102,34 @@
                            </div>
                        {% endif %}

+                        {% if position.seat %}
+                            <div class="row">
+                                <div class="col-sm-3">
+                                    <strong>{% trans "Seat" %}</strong>
+                                </div>
+                                <div class="col-sm-5">
+                                    {{ position.seat }}
+                                </div>
+                                <div class="col-sm-4">
+                                    {% bootstrap_field position.form.seat layout='inline' %}
+                                </div>
+                            </div>
+                        {% endif %}
+                        <div class="row">
+                            <div class="col-sm-3">
+                                <strong>{% trans "Product" %}</strong>
+                            </div>
+                            <div class="col-sm-5">
+                                {{ position.item }}
+                                {% if position.variation %}
+                                    – {{ position.variation }}
+                                {% endif %}
+                            </div>
+                            <div class="col-sm-4">
+                                {% bootstrap_field position.form.itemvar layout='inline' %}
+                            </div>
+                        </div>
+
                        <div class="row">
                            <div class="col-sm-3">
                                <strong>{% trans "Price" %}</strong>
@@ -182,6 +196,7 @@
                    {% if add_form.subevent %}
                        {% bootstrap_field add_form.subevent layout="control" %}
                    {% endif %}
+                    {% bootstrap_field add_form.seat layout="control" %}
                </div>
            </div>
        </div>
--- a/src/pretix/control/templates/pretixcontrol/order/index.html
+++ b/src/pretix/control/templates/pretixcontrol/order/index.html
@@ -258,6 +258,15 @@
                                        <span class="fa fa-fw fa-check" data-toggle="tooltip_html" title="{{ c.list.name }}<br>{% blocktrans trimmed with date=c.datetime|date:'SHORT_DATETIME_FORMAT' %}First scanned: {{ date }}{% endblocktrans %}"></span>
                                    {% endfor %}
                                {% endif %}
+                                {% if line.seat %}
+                                    <br />
+                                    <svg xmlns="http://www.w3.org/2000/svg" width="18" height="14" viewBox="0 0 4.7624999 3.7041668" class="svg-icon">
+                                        <path
+                                                style="fill:black"
+                                                d="m 1.9592032,1.8522629e-4 c -0.21468,0 -0.38861,0.17394000371 -0.38861,0.38861000371 0,0.21466 0.17393,0.38861 0.38861,0.38861 0.21468,0 0.3886001,-0.17395 0.3886001,-0.38861 0,-0.21467 -0.1739201,-0.38861000371 -0.3886001,-0.38861000371 z m 0.1049,0.84543000371 c -0.20823,-0.0326 -0.44367,0.12499 -0.39998,0.40462997 l 0.20361,1.01854 c 0.0306,0.15316 0.15301,0.28732 0.3483,0.28732 h 0.8376701 v 0.92708 c 0,0.29313 0.41187,0.29447 0.41187,0.005 v -1.19115 c 0,-0.14168 -0.0995,-0.29507 -0.29094,-0.29507 l -0.65578,-10e-4 -0.1757,-0.87644 C 2.3042533,0.95300523 2.1890432,0.86500523 2.0641032,0.84547523 Z m -0.58549,0.44906997 c -0.0946,-0.0134 -0.20202,0.0625 -0.17829,0.19172 l 0.18759,0.91054 c 0.0763,0.33956 0.36802,0.55914 0.66042,0.55914 h 0.6015201 c 0.21356,0 0.21448,-0.32143 -0.003,-0.32143 H 2.1954632 c -0.19911,0 -0.36364,-0.11898 -0.41341,-0.34107 l -0.17777,-0.87126 c -0.0165,-0.0794 -0.0688,-0.11963 -0.12557,-0.12764 z"/>
+                                    </svg>
+                                    {{ line.seat }}
+                                {% endif %}
                                {% if line.voucher %}
                                    <br/><span class="fa fa-tags"></span> {% trans "Voucher code used:" %}
                                    <a href="{% url "control:event.voucher" event=request.event.slug organizer=request.event.organizer.slug voucher=line.voucher.pk %}">
--- a/src/pretix/control/templates/pretixcontrol/subevents/bulk.html
+++ b/src/pretix/control/templates/pretixcontrol/subevents/bulk.html
@@ -434,6 +434,12 @@
                    </button>
                </p>
        </fieldset>
+        <fieldset>
+            <legend>{% trans "Additional settings" %}</legend>
+            {% for f in plugin_forms %}
+                {% bootstrap_form f layout="control" %}
+            {% endfor %}
+        </fieldset>
        <div class="form-group submit-group">
            <button type="submit" class="btn btn-primary btn-save">
                {% trans "Save" %}
--- a/src/pretix/control/templates/pretixcontrol/subevents/detail.html
+++ b/src/pretix/control/templates/pretixcontrol/subevents/detail.html
@@ -192,6 +192,12 @@
                            </button>
                        </p>
                </fieldset>
+                <fieldset>
+                    <legend>{% trans "Additional settings" %}</legend>
+                    {% for f in plugin_forms %}
+                        {% bootstrap_form f layout="control" %}
+                    {% endfor %}
+                </fieldset>
            </div>
            {% if subevent.pk %}
                <div class="col-xs-12 col-lg-2">
--- a/src/pretix/control/urls.py
+++ b/src/pretix/control/urls.py
@@ -140,6 +140,7 @@ urlpatterns = [
        url(r'^pdf/editor/(?P<filename>[^/]+).pdf$', pdf.PdfView.as_view(), name='pdf.background'),
        url(r'^subevents/$', subevents.SubEventList.as_view(), name='event.subevents'),
        url(r'^subevents/select2$', typeahead.subevent_select2, name='event.subevents.select2'),
+        url(r'^seats/select2$', typeahead.seat_select2, name='event.seats.select2'),
        url(r'^subevents/(?P<subevent>\d+)/$', subevents.SubEventUpdate.as_view(), name='event.subevent'),
        url(r'^subevents/(?P<subevent>\d+)/delete$', subevents.SubEventDelete.as_view(),
            name='event.subevent.delete'),
--- a/src/pretix/control/views/orders.py
+++ b/src/pretix/control/views/orders.py
@@ -1236,7 +1236,8 @@ class OrderChange(OrderView):
                    ocm.add_position(item, variation,
                                     self.add_form.cleaned_data['price'],
                                     self.add_form.cleaned_data.get('addon_to'),
-                                     self.add_form.cleaned_data.get('subevent'))
+                                     self.add_form.cleaned_data.get('subevent'),
+                                     self.add_form.cleaned_data.get('seat'))
                except OrderError as e:
                    self.add_form.custom_error = str(e)
                    return False
@@ -1266,6 +1267,9 @@ class OrderChange(OrderView):
                    if item != p.item or variation != p.variation:
                        ocm.change_item(p, item, variation)

+                if p.seat and p.form.cleaned_data['seat'] and p.form.cleaned_data['seat'] != p.seat:
+                    ocm.change_seat(p, p.form.cleaned_data['seat'])
+
                if self.request.event.has_subevents and p.form.cleaned_data['subevent'] and p.form.cleaned_data['subevent'] != p.subevent:
                    ocm.change_subevent(p, p.form.cleaned_data['subevent'])

--- a/src/pretix/control/views/subevents.py
+++ b/src/pretix/control/views/subevents.py
@@ -3,6 +3,7 @@ from datetime import datetime

 from dateutil.rrule import DAILY, MONTHLY, WEEKLY, YEARLY, rrule, rruleset
 from django.contrib import messages
+from django.core.files import File
 from django.db import transaction
 from django.db.models import F, IntegerField, OuterRef, Prefetch, Subquery, Sum
 from django.db.models.functions import Coalesce
@@ -32,6 +33,7 @@ from pretix.control.forms.subevents import (
    SubEventMetaValueForm,
 )
 from pretix.control.permissions import EventPermissionRequiredMixin
+from pretix.control.signals import subevent_forms
 from pretix.control.views import PaginationMixin
 from pretix.control.views.event import MetaDataEditorMixin
 from pretix.helpers.models import modelcopy
@@ -135,6 +137,16 @@ class SubEventEditorMixin(MetaDataEditorMixin):
    meta_form = SubEventMetaValueForm
    meta_model = SubEventMetaValue

+    @cached_property
+    def plugin_forms(self):
+        forms = []
+        for rec, resp in subevent_forms.send(sender=self.request.event, subevent=self.object, request=self.request):
+            if isinstance(resp, (list, tuple)):
+                forms.extend(resp)
+            else:
+                forms.append(resp)
+        return forms
+
    def _make_meta_form(self, p, val_instances):
        if not hasattr(self, '_default_meta'):
            self._default_meta = self.request.event.meta_data
@@ -294,6 +306,7 @@ class SubEventEditorMixin(MetaDataEditorMixin):
        ctx['cl_formset'] = self.cl_formset
        ctx['itemvar_forms'] = self.itemvar_forms
        ctx['meta_forms'] = self.meta_forms
+        ctx['plugin_forms'] = self.plugin_forms
        return ctx

    @cached_property
@@ -347,7 +360,7 @@ class SubEventEditorMixin(MetaDataEditorMixin):
    def is_valid(self, form):
        return form.is_valid() and all([f.is_valid() for f in self.itemvar_forms]) and self.formset.is_valid() and (
            all([f.is_valid() for f in self.meta_forms])
-        ) and self.cl_formset.is_valid()
+        ) and self.cl_formset.is_valid() and all(f.is_valid() for f in self.plugin_forms)


 class SubEventUpdate(EventPermissionRequiredMixin, SubEventEditorMixin, UpdateView):
@@ -361,9 +374,9 @@ class SubEventUpdate(EventPermissionRequiredMixin, SubEventEditorMixin, UpdateVi
        self.object = self.get_object()
        form = self.get_form()
        if self.is_valid(form):
-            return self.form_valid(form)
-        else:
-            return self.form_invalid(form)
+            r = self.form_valid(form)
+            return r
+        return self.form_invalid(form)

    def get_object(self, queryset=None) -> SubEvent:
        try:
@@ -384,12 +397,23 @@ class SubEventUpdate(EventPermissionRequiredMixin, SubEventEditorMixin, UpdateVi
            # TODO: LogEntry?

        messages.success(self.request, _('Your changes have been saved.'))
-        if form.has_changed():
+        if form.has_changed() or any(f.has_changed() for f in self.plugin_forms):
+            data = {
+                k: form.cleaned_data.get(k) for k in form.changed_data
+            }
+            for f in self.plugin_forms:
+                data.update({
+                    k: (f.cleaned_data.get(k).name
+                        if isinstance(f.cleaned_data.get(k), File)
+                        else f.cleaned_data.get(k))
+                    for k in f.changed_data
+                })
            self.object.log_action(
-                'pretix.subevent.changed', user=self.request.user, data={
-                    k: form.cleaned_data.get(k) for k in form.changed_data
-                }
+                'pretix.subevent.changed', user=self.request.user, data=data
            )
+        for f in self.plugin_forms:
+            f.subevent = self.object
+            f.save()
        return super().form_valid(form)

    def get_success_url(self) -> str:
@@ -416,8 +440,7 @@ class SubEventCreate(SubEventEditorMixin, EventPermissionRequiredMixin, CreateVi
        form = self.get_form()
        if self.is_valid(form):
            return self.form_valid(form)
-        else:
-            return self.form_invalid(form)
+        return self.form_invalid(form)

    def get_success_url(self) -> str:
        return reverse('control:event.subevents', kwargs={
@@ -442,7 +465,16 @@ class SubEventCreate(SubEventEditorMixin, EventPermissionRequiredMixin, CreateVi
        messages.success(self.request, pgettext_lazy('subevent', 'The new date has been created.'))
        ret = super().form_valid(form)
        self.object = form.instance
-        form.instance.log_action('pretix.subevent.added', data=dict(form.cleaned_data), user=self.request.user)
+
+        data = dict(form.cleaned_data)
+        for f in self.plugin_forms:
+            data.update({
+                k: (f.cleaned_data.get(k).name
+                    if isinstance(f.cleaned_data.get(k), File)
+                    else f.cleaned_data.get(k))
+                for k in f.cleaned_data
+            })
+        form.instance.log_action('pretix.subevent.added', data=dict(data), user=self.request.user)

        self.save_formset(form.instance)
        self.save_cl_formset(form.instance)
@@ -452,6 +484,9 @@ class SubEventCreate(SubEventEditorMixin, EventPermissionRequiredMixin, CreateVi
        for f in self.meta_forms:
            f.instance.subevent = form.instance
        self.save_meta()
+        for f in self.plugin_forms:
+            f.subevent = form.instance
+            f.save()
        return ret

    @cached_property
@@ -657,7 +692,6 @@ class SubEventBulkCreate(SubEventEditorMixin, EventPermissionRequiredMixin, Crea

    @transaction.atomic
    def form_valid(self, form):
-
        tz = self.request.event.timezone
        cnt = 0
        for rdate in self.get_rrule_set():
@@ -685,7 +719,15 @@ class SubEventBulkCreate(SubEventEditorMixin, EventPermissionRequiredMixin, Crea
                else None
            )
            se.save()
-            se.log_action('pretix.subevent.added', data=dict(form.cleaned_data), user=self.request.user)
+            data = dict(form.cleaned_data)
+            for f in self.plugin_forms:
+                data.update({
+                    k: (f.cleaned_data.get(k).name
+                        if isinstance(f.cleaned_data.get(k), File)
+                        else f.cleaned_data.get(k))
+                    for k in f.cleaned_data
+                })
+            se.log_action('pretix.subevent.added', data=data, user=self.request.user)

            for f in self.meta_forms:
                if f.cleaned_data.get('value'):
@@ -731,6 +773,11 @@ class SubEventBulkCreate(SubEventEditorMixin, EventPermissionRequiredMixin, Crea
                i.subevent = se
                i.save()

+            for f in self.plugin_forms:
+                f.is_valid()
+                f.subevent = se
+                f.save()
+
            cnt += 1

        messages.success(self.request, pgettext_lazy('subevent', '{} new dates have been created.').format(cnt))
@@ -742,7 +789,8 @@ class SubEventBulkCreate(SubEventEditorMixin, EventPermissionRequiredMixin, Crea
    def post(self, request, *args, **kwargs):
        form = self.get_form()
        self.object = SubEvent(event=self.request.event)
+
        if self.is_valid(form):
            return self.form_valid(form)
-        else:
-            return self.form_invalid(form)
+
+        return self.form_invalid(form)
--- a/src/pretix/control/views/typeahead.py
+++ b/src/pretix/control/views/typeahead.py
@@ -11,7 +11,7 @@ from django.utils.formats import get_format
 from django.utils.timezone import make_aware
 from django.utils.translation import pgettext, ugettext as _

-from pretix.base.models import Order, Organizer, User, Voucher
+from pretix.base.models import Order, Organizer, SubEvent, User, Voucher
 from pretix.control.forms.event import EventWizardCopyForm
 from pretix.control.permissions import event_permission_required
 from pretix.helpers.daterange import daterange
@@ -221,6 +221,46 @@ def nav_context_list(request):
    return JsonResponse(doc)


+@event_permission_required("can_view_orders")
+def seat_select2(request, **kwargs):
+    query = request.GET.get('query', '')
+    try:
+        page = int(request.GET.get('page', '1'))
+    except ValueError:
+        page = 1
+
+    if request.event.has_subevents:
+        try:
+            qs = request.event.subevents.get(active=True, pk=request.GET.get('subevent', 0)).free_seats
+        except SubEvent.DoesNotExist:
+            qs = request.event.seats.none()
+    else:
+        qs = request.event.free_seats
+    qs = qs.filter(
+        Q(name__icontains=query) | Q(seat_guid__icontains=query)
+    ).order_by('name').select_related('product', 'subevent')
+
+    total = qs.count()
+    pagesize = 20
+    offset = (page - 1) * pagesize
+    doc = {
+        'results': [
+            {
+                'id': e.pk,
+                'text': '{} ({})'.format(e.name, str(e.product)),
+                'product': e.product_id,
+                'event': str(e.subevent) if e.subevent else ''
+
+            }
+            for e in qs[offset:offset + pagesize]
+        ],
+        'pagination': {
+            "more": total >= (offset + pagesize)
+        }
+    }
+    return JsonResponse(doc)
+
+
@event_permission_required(None)
 def subevent_select2(request, **kwargs):
    query = request.GET.get('query', '')
--- a/src/pretix/icons/seat.svg
+++ b/src/pretix/icons/seat.svg
@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<svg xmlns="http://www.w3.org/2000/svg" width="18" height="14" viewBox="0 0 4.7624999 3.7041668">
+  <path
+     style="fill:black"
+     d="m 1.9592032,1.8522629e-4 c -0.21468,0 -0.38861,0.17394000371 -0.38861,0.38861000371 0,0.21466 0.17393,0.38861 0.38861,0.38861 0.21468,0 0.3886001,-0.17395 0.3886001,-0.38861 0,-0.21467 -0.1739201,-0.38861000371 -0.3886001,-0.38861000371 z m 0.1049,0.84543000371 c -0.20823,-0.0326 -0.44367,0.12499 -0.39998,0.40462997 l 0.20361,1.01854 c 0.0306,0.15316 0.15301,0.28732 0.3483,0.28732 h 0.8376701 v 0.92708 c 0,0.29313 0.41187,0.29447 0.41187,0.005 v -1.19115 c 0,-0.14168 -0.0995,-0.29507 -0.29094,-0.29507 l -0.65578,-10e-4 -0.1757,-0.87644 C 2.3042533,0.95300523 2.1890432,0.86500523 2.0641032,0.84547523 Z m -0.58549,0.44906997 c -0.0946,-0.0134 -0.20202,0.0625 -0.17829,0.19172 l 0.18759,0.91054 c 0.0763,0.33956 0.36802,0.55914 0.66042,0.55914 h 0.6015201 c 0.21356,0 0.21448,-0.32143 -0.003,-0.32143 H 2.1954632 c -0.19911,0 -0.36364,-0.11898 -0.41341,-0.34107 l -0.17777,-0.87126 c -0.0165,-0.0794 -0.0688,-0.11963 -0.12557,-0.12764 z"/>
+</svg>
--- a/src/pretix/presale/signals.py
+++ b/src/pretix/presale/signals.py
@@ -222,6 +222,18 @@ As with all plugin signals, the ``sender`` keyword argument will contain the eve
 receivers are expected to return HTML.
 """

+render_seating_plan = EventPluginSignal(
+    providing_args=["request", "subevent", "voucher"]
+)
+"""
+This signal is sent out to render a seating plan, if one is configured for the specific event.
+You will be passed the ``request`` as a keyword argument. If applicable, a ``subevent`` or
+``voucher`` argument might be given.
+
+As with all plugin signals, the ``sender`` keyword argument will contain the event. The
+receivers are expected to return HTML.
+"""
+
 front_page_bottom = EventPluginSignal(
    providing_args=[]
 )
--- a/src/pretix/presale/templates/pretixpresale/base.html
+++ b/src/pretix/presale/templates/pretixpresale/base.html
@@ -19,20 +19,7 @@
        {% endcompress %}
    {% endif %}

-    {% compress js %}
-        <script type="text/javascript" src="{% static "jquery/js/jquery-2.1.1.min.js" %}"></script>
-        <script type="text/javascript" src="{% static "moment/moment-with-locales.js" %}"></script>
-        <script type="text/javascript" src="{% static "js/jquery.formset.js" %}"></script>
-        <script type="text/javascript" src="{% static "bootstrap/js/bootstrap.js" %}"></script>
-        <script type="text/javascript" src="{% static "datetimepicker/bootstrap-datetimepicker.js" %}"></script>
-        <script type="text/javascript" src="{% static "pretixcontrol/js/jquery.qrcode.min.js" %}"></script>
-        <script type="text/javascript" src="{% static "pretixpresale/js/ui/questions.js" %}"></script>
-        <script type="text/javascript" src="{% static "pretixpresale/js/ui/main.js" %}"></script>
-        <script type="text/javascript" src="{% static "pretixbase/js/asynctask.js" %}"></script>
-        <script type="text/javascript" src="{% static "pretixbase/js/details.js" %}"></script>
-        <script type="text/javascript" src="{% static "pretixpresale/js/ui/cart.js" %}"></script>
-        <script type="text/javascript" src="{% static "lightbox/js/lightbox.min.js" %}"></script>
-    {% endcompress %}
+    {% include "pretixpresale/fragment_js.html" %}
    <meta name="referrer" content="origin">
    {{ html_head|safe }}
    <meta name="viewport" content="width=device-width, initial-scale=1, user-scalable=0">
@@ -79,20 +66,7 @@
        {% include "pretixpresale/base_footer.html" %}
    </footer>
 </div>
-<div id="ajaxerr">
-</div>
-<div id="loadingmodal">
-    <div class="modal-card">
-        <div class="modal-card-icon">
-            <i class="fa fa-cog big-rotating-icon"></i>
-        </div>
-        <div class="modal-card-content">
-            <h3></h3>
-            <p class="text"></p>
-            <p class="status">{% trans "If this takes longer than a few minutes, please contact us." %}</p>
-        </div>
-    </div>
-</div>
+{% include "pretixpresale/fragment_modals.html" %}
 {% if DEBUG %}
    <script type="text/javascript" src="{% url 'javascript-catalog' lang=request.LANGUAGE_CODE %}" async></script>
 {% else %}
--- a/src/pretix/presale/templates/pretixpresale/event/fragment_cart.html
+++ b/src/pretix/presale/templates/pretixpresale/event/fragment_cart.html
@@ -13,11 +13,20 @@
            {% if line.variation %}
                – {{ line.variation }}
            {% endif %}
+            {% if line.seat %}
+                <br />
+                <svg xmlns="http://www.w3.org/2000/svg" width="18" height="14" viewBox="0 0 4.7624999 3.7041668" class="svg-icon">
+                    <path
+                            style="fill:black"
+                            d="m 1.9592032,1.8522629e-4 c -0.21468,0 -0.38861,0.17394000371 -0.38861,0.38861000371 0,0.21466 0.17393,0.38861 0.38861,0.38861 0.21468,0 0.3886001,-0.17395 0.3886001,-0.38861 0,-0.21467 -0.1739201,-0.38861000371 -0.3886001,-0.38861000371 z m 0.1049,0.84543000371 c -0.20823,-0.0326 -0.44367,0.12499 -0.39998,0.40462997 l 0.20361,1.01854 c 0.0306,0.15316 0.15301,0.28732 0.3483,0.28732 h 0.8376701 v 0.92708 c 0,0.29313 0.41187,0.29447 0.41187,0.005 v -1.19115 c 0,-0.14168 -0.0995,-0.29507 -0.29094,-0.29507 l -0.65578,-10e-4 -0.1757,-0.87644 C 2.3042533,0.95300523 2.1890432,0.86500523 2.0641032,0.84547523 Z m -0.58549,0.44906997 c -0.0946,-0.0134 -0.20202,0.0625 -0.17829,0.19172 l 0.18759,0.91054 c 0.0763,0.33956 0.36802,0.55914 0.66042,0.55914 h 0.6015201 c 0.21356,0 0.21448,-0.32143 -0.003,-0.32143 H 2.1954632 c -0.19911,0 -0.36364,-0.11898 -0.41341,-0.34107 l -0.17777,-0.87126 c -0.0165,-0.0794 -0.0688,-0.11963 -0.12557,-0.12764 z"/>
+                </svg>
+                {{ line.seat }}
+            {% endif %}
            {% if line.voucher %}
-                <br /><span class="fa fa-tags"></span> {% trans "Voucher code used:" %} {{ line.voucher.code }}
+                <br /><span class="fa fa-tags fa-fw"></span> {% trans "Voucher code used:" %} {{ line.voucher.code }}
            {% endif %}
            {% if line.subevent %}
-                <br /><span class="fa fa-calendar"></span> {{ line.subevent.name }} &middot; {{ line.subevent.get_date_range_display }}
+                <br /><span class="fa fa-calendar fa-fw"></span> {{ line.subevent.name }} &middot; {{ line.subevent.get_date_range_display }}
                {% if event.settings.show_times %}
                    <span class="fa fa-clock-o"></span>
                    {{ line.subevent.date_from|date:"TIME_FORMAT" }}
@@ -116,7 +125,7 @@
                        <input type="hidden" name="price_{{ line.item.id }}"
                                value="{% if event.settings.display_net_prices %}{{ line.net_price }}{% else %}{{ line.price }}{% endif %}" />
                    {% endif %}
-                    <button class="btn btn-mini btn-link" title="{% trans "Add one more" %}">
+                    <button class="btn btn-mini btn-link" title="{% trans "Add one more" %}" {% if line.seat %}disabled{% endif %}>
                        <i class="fa fa-plus"></i>
                    </button>
                </form>
--- a/src/pretix/presale/templates/pretixpresale/event/fragment_product_list.html
+++ b/src/pretix/presale/templates/pretixpresale/event/fragment_product_list.html
@@ -141,7 +141,7 @@
                                    </div>
                                    {% elif var.cached_availability.0 == 100 %}
                                    <div class="col-md-2 col-xs-6 availability-box available">
-                                        {% if item.max_per_order == 1 %}
+										{% if item.max_per_order == 1 %}
                                            <label class="item-checkbox-label">
                                                <input type="checkbox" value="1"
                                                       {% if not ev.presale_is_running %}disabled{% endif %}
@@ -255,7 +255,7 @@
                        </div>
                        {% elif item.cached_availability.0 == 100 %}
                        <div class="col-md-2 col-xs-6 availability-box available">
-                            {% if item.max_per_order == 1 %}
+							{% if item.max_per_order == 1 %}
                                <label class="item-checkbox-label">
                                    <input type="checkbox" value="1" {% if itemnum == 1 %}checked{% endif %}
                                           {% if not ev.presale_is_running %}disabled{% endif %}
--- a/src/pretix/presale/templates/pretixpresale/event/index.html
+++ b/src/pretix/presale/templates/pretixpresale/event/index.html
@@ -219,6 +219,13 @@
                    action="{% eventurl request.event "presale:event.cart.add" cart_namespace=cart_namespace %}?next={{ cart_redirect|urlencode }}">
                {% csrf_token %}
                <input type="hidden" name="subevent" value="{{ subevent.id|default_if_none:"" }}" />
+                {% if ev.seating_plan_id %}
+                    {% if event.has_subevents %}
+                        {% eventsignal event "pretix.presale.signals.render_seating_plan" request=request subevent=subevent %}
+                    {% else %}
+                        {% eventsignal event "pretix.presale.signals.render_seating_plan" request=request %}
+                    {% endif %}
+                {% endif %}
                {% include "pretixpresale/event/fragment_product_list.html" %}
                {% if ev.presale_is_running and display_add_to_cart %}
                    <section class="front-page">
--- a/src/pretix/presale/templates/pretixpresale/event/seatingplan.html
+++ b/src/pretix/presale/templates/pretixpresale/event/seatingplan.html
@@ -0,0 +1,47 @@
+{% load i18n %}
+{% load static %}
+{% load eventurl %}
+{% load compress %}
+{% load eventsignal %}
+{% load statici18n %}
+<!DOCTYPE html>
+<html>
+<head>
+    {% if css_file %}
+        <link rel="stylesheet" type="text/css" href="{{ css_file }}"/>
+    {% else %}
+        {% compress css %}
+            <link rel="stylesheet" type="text/x-scss" href="{% static "pretixpresale/scss/main.scss" %}"/>
+        {% endcompress %}
+    {% endif %}
+    {% include "pretixpresale/fragment_js.html" %}
+    <meta name="referrer" content="origin">
+    <meta name="viewport" content="width=device-width, initial-scale=1, user-scalable=0">
+</head>
+<body class="full-screen-seating" data-locale="{{ request.LANGUAGE_CODE }}">
+<form method="post" data-asynctask
+      data-asynctask-headline="{% trans "We're now trying to reserve this for you!" %}"
+      data-asynctask-text="{% blocktrans with time=event.settings.reservation_time %}Once the items are in your cart, you will have {{ time }} minutes to complete your purchase.{% endblocktrans %}"
+      action="{% eventurl request.event "presale:event.cart.add" cart_namespace=cart_namespace %}?next={{ cart_redirect|urlencode }}">
+    {% csrf_token %}
+    <input type="hidden" name="subevent" value="{{ subevent.id|default_if_none:"" }}"/>
+    {% if event.has_subevents %}
+        {% eventsignal event "pretix.presale.signals.render_seating_plan" request=request subevent=subevent %}
+    {% else %}
+        {% eventsignal event "pretix.presale.signals.render_seating_plan" request=request %}
+    {% endif %}
+</form>
+{% include "pretixpresale/fragment_modals.html" %}
+{% if DEBUG %}
+    <script type="text/javascript" src="{% url 'javascript-catalog' lang=request.LANGUAGE_CODE %}" async></script>
+{% else %}
+    <script src="{% statici18n LANGUAGE_CODE %}" async></script>
+{% endif %}
+{% if request.session.iframe_session %}
+    {% compress js %}
+        <script type="text/javascript" src="{% static "iframeresizer/iframeResizer.contentWindow.js" %}"></script>
+    {% endcompress %}
+{% endif %}
+{{ html_foot|safe }}
+</body>
+</html>
--- a/src/pretix/presale/templates/pretixpresale/event/voucher.html
+++ b/src/pretix/presale/templates/pretixpresale/event/voucher.html
@@ -29,6 +29,14 @@
            <input type="hidden" name="subevent" value="{{ subevent.id|default_if_none:"" }}" />
            <input type="hidden" name="_voucher_code" value="{{ voucher.code }}">

+            {% if voucher.seating_available %}
+                {% if event.has_subevents %}
+                    {% eventsignal event "pretix.presale.signals.render_seating_plan" request=request subevent=subevent voucher=voucher %}
+                {% else %}
+                    {% eventsignal event "pretix.presale.signals.render_seating_plan" request=request voucher=voucher %}
+                {% endif %}
+            {% endif %}
+
            {% for tup in items_by_category %}
                <section>
                    {% if tup.0 %}
--- a/src/pretix/presale/templates/pretixpresale/fragment_js.html
+++ b/src/pretix/presale/templates/pretixpresale/fragment_js.html
@@ -0,0 +1,16 @@
+{% load static %}
+{% load compress %}
+{% compress js %}
+    <script type="text/javascript" src="{% static "jquery/js/jquery-2.1.1.min.js" %}"></script>
+    <script type="text/javascript" src="{% static "moment/moment-with-locales.js" %}"></script>
+    <script type="text/javascript" src="{% static "js/jquery.formset.js" %}"></script>
+    <script type="text/javascript" src="{% static "bootstrap/js/bootstrap.js" %}"></script>
+    <script type="text/javascript" src="{% static "datetimepicker/bootstrap-datetimepicker.js" %}"></script>
+    <script type="text/javascript" src="{% static "pretixcontrol/js/jquery.qrcode.min.js" %}"></script>
+    <script type="text/javascript" src="{% static "pretixpresale/js/ui/questions.js" %}"></script>
+    <script type="text/javascript" src="{% static "pretixpresale/js/ui/main.js" %}"></script>
+    <script type="text/javascript" src="{% static "pretixbase/js/asynctask.js" %}"></script>
+    <script type="text/javascript" src="{% static "pretixbase/js/details.js" %}"></script>
+    <script type="text/javascript" src="{% static "pretixpresale/js/ui/cart.js" %}"></script>
+    <script type="text/javascript" src="{% static "lightbox/js/lightbox.min.js" %}"></script>
+{% endcompress %}
--- a/src/pretix/presale/templates/pretixpresale/fragment_modals.html
+++ b/src/pretix/presale/templates/pretixpresale/fragment_modals.html
@@ -0,0 +1,15 @@
+{% load i18n %}
+<div id="ajaxerr">
+</div>
+<div id="loadingmodal">
+    <div class="modal-card">
+        <div class="modal-card-icon">
+            <i class="fa fa-cog big-rotating-icon"></i>
+        </div>
+        <div class="modal-card-content">
+            <h3></h3>
+            <p class="text"></p>
+            <p class="status">{% trans "If this takes longer than a few minutes, please contact us." %}</p>
+        </div>
+    </div>
+</div>
--- a/src/pretix/presale/urls.py
+++ b/src/pretix/presale/urls.py
@@ -27,6 +27,10 @@ frame_wrapped_urls = [
        name='event.checkout'),
    url(r'^redeem/?$', pretix.presale.views.cart.RedeemView.as_view(),
        name='event.redeem'),
+    url(r'^seatingframe/$', pretix.presale.views.event.SeatingPlanView.as_view(),
+        name='event.seatingplan'),
+    url(r'^(?P<subevent>[0-9]+)/seatingframe/$', pretix.presale.views.event.SeatingPlanView.as_view(),
+        name='event.seatingplan'),
    url(r'^(?P<subevent>[0-9]+)/$', pretix.presale.views.event.EventIndex.as_view(), name='event.index'),
    url(r'^waitinglist', pretix.presale.views.waiting.WaitingView.as_view(), name='event.waitinglist'),
    url(r'^$', pretix.presale.views.event.EventIndex.as_view(), name='event.index'),
--- a/src/pretix/presale/views/init.py
+++ b/src/pretix/presale/views/init.py
@@ -59,7 +59,7 @@ class CartMixin:
            cartpos = queryset.order_by(
                'item__category__position', 'item__category_id', 'item__position', 'item__name', 'variation__value'
            ).select_related(
-                'item', 'variation', 'addon_to', 'subevent', 'subevent__event', 'subevent__event__organizer'
+                'item', 'variation', 'addon_to', 'subevent', 'subevent__event', 'subevent__event__organizer', 'seat'
            ).prefetch_related(
                *prefetch
            )
@@ -103,13 +103,13 @@ class CartMixin:
            )
            addon_penalty = 1 if pos.addon_to else 0
            if downloads or pos.pk in has_addons or pos.addon_to:
-                return i, addon_penalty, pos.pk, 0, 0, 0, 0, (pos.subevent_id or 0)
+                return i, addon_penalty, pos.pk, 0, 0, 0, 0, (pos.subevent_id or 0), pos.seat_id
            if answers and (has_attendee_data or pos.item.questions.all()):
-                return i, addon_penalty, pos.pk, 0, 0, 0, 0, (pos.subevent_id or 0)
+                return i, addon_penalty, pos.pk, 0, 0, 0, 0, (pos.subevent_id or 0), pos.seat_id

            return (
                0, addon_penalty, 0, pos.item_id, pos.variation_id, pos.price, (pos.voucher_id or 0),
-                (pos.subevent_id or 0)
+                (pos.subevent_id or 0), pos.seat_id
            )

        positions = []
--- a/src/pretix/presale/views/cart.py
+++ b/src/pretix/presale/views/cart.py
@@ -90,10 +90,26 @@ class CartActionMixin:
        if value.strip() == '' or '_' not in key:
            return

-        if not key.startswith('item_') and not key.startswith('variation_'):
+        if not key.startswith('item_') and not key.startswith('variation_') and not key.startswith('seat_'):
            return

        parts = key.split("_")
+        price = self.request.POST.get('price_' + "_".join(parts[1:]), "")
+
+        if key.startswith('seat_'):
+            try:
+                return {
+                    'item': int(parts[1]),
+                    'variation': int(parts[2]) if len(parts) > 2 else None,
+                    'count': 1,
+                    'seat': value,
+                    'price': price,
+                    'voucher': voucher,
+                    'subevent': self.request.POST.get("subevent")
+                }
+            except ValueError:
+                raise CartError(_('Please enter numbers only.'))
+
        try:
            amount = int(value)
        except ValueError:
@@ -103,7 +119,6 @@ class CartActionMixin:
        elif amount == 0:
            return

-        price = self.request.POST.get('price_' + "_".join(parts[1:]), "")
        if key.startswith('item_'):
            try:
                return {
@@ -131,8 +146,7 @@ class CartActionMixin:

    def _items_from_post_data(self):
        """
-        Parses the POST data and returns a list of tuples in the
-        form (item id, variation id or None, number)
+        Parses the POST data and returns a list of dictionaries
        """

        # Compatibility patch that makes the frontend code a lot easier
--- a/src/pretix/presale/views/event.py
+++ b/src/pretix/presale/views/event.py
@@ -7,7 +7,7 @@ from importlib import import_module
 import pytz
 from django.conf import settings
 from django.core.exceptions import PermissionDenied
-from django.db.models import Count, Prefetch
+from django.db.models import Count, Exists, OuterRef, Prefetch
 from django.http import Http404, HttpResponse
 from django.shortcuts import get_object_or_404, redirect, render
 from django.utils.decorators import method_decorator
@@ -17,7 +17,7 @@ from django.views import View
 from django.views.decorators.csrf import csrf_exempt
 from django.views.generic import TemplateView

-from pretix.base.models import ItemVariation, Quota
+from pretix.base.models import ItemVariation, Quota, SeatCategoryMapping
 from pretix.base.models.event import SubEvent
 from pretix.base.models.items import ItemBundle
 from pretix.multidomain.urlreverse import eventreverse
@@ -49,7 +49,7 @@ def item_group_by_category(items):
    )


-def get_grouped_items(event, subevent=None, voucher=None, channel='web'):
+def get_grouped_items(event, subevent=None, voucher=None, channel='web', require_seat=0):
    items = event.items.using(settings.DATABASE_REPLICA).filter_available(channel=channel, voucher=voucher).select_related(
        'category', 'tax_rule',  # for re-grouping
    ).prefetch_related(
@@ -81,10 +81,20 @@ def get_grouped_items(event, subevent=None, voucher=None, channel='web'):
                 ).distinct()),
    ).annotate(
        quotac=Count('quotas'),
-        has_variations=Count('variations')
+        has_variations=Count('variations'),
+        requires_seat=Exists(
+            SeatCategoryMapping.objects.filter(
+                product_id=OuterRef('pk'),
+                subevent=subevent
+            )
+        )
    ).filter(
-        quotac__gt=0
+        quotac__gt=0,
    ).order_by('category__position', 'category_id', 'position', 'name')
+    if require_seat:
+        items = items.filter(requires_seat__gt=0)
+    else:
+        items = items.filter(requires_seat=0)
    display_add_to_cart = False
    external_quota_cache = event.cache.get('item_quota_cache')
    quota_cache = external_quota_cache or {}
@@ -342,6 +352,52 @@ class EventIndex(EventViewMixin, EventListMixin, CartMixin, TemplateView):
        return context


+@method_decorator(allow_frame_if_namespaced, 'dispatch')
+@method_decorator(iframe_entry_view_wrapper, 'dispatch')
+class SeatingPlanView(EventViewMixin, TemplateView):
+    template_name = "pretixpresale/event/seatingplan.html"
+
+    def get(self, request, *args, **kwargs):
+        from pretix.presale.views.cart import get_or_create_cart_id
+
+        self.subevent = None
+        if request.GET.get('src', '') == 'widget' and 'take_cart_id' in request.GET:
+            # User has clicked "Open in a new tab" link in widget
+            get_or_create_cart_id(request)
+            return redirect(eventreverse(request.event, 'presale:event.seatingplan', kwargs=kwargs))
+        elif request.GET.get('iframe', '') == '1' and 'take_cart_id' in request.GET:
+            # Widget just opened, a cart already exists. Let's to a stupid redirect to check if cookies are disabled
+            get_or_create_cart_id(request)
+            return redirect(eventreverse(request.event, 'presale:event.seatingplan', kwargs=kwargs) + '?require_cookie=true&cart_id={}'.format(
+                request.GET.get('take_cart_id')
+            ))
+        elif request.GET.get('iframe', '') == '1' and len(self.request.GET.get('widget_data', '{}')) > 3:
+            # We've been passed data from a widget, we need to create a cart session to store it.
+            get_or_create_cart_id(request)
+
+        if request.event.has_subevents:
+            if 'subevent' in kwargs:
+                self.subevent = request.event.subevents.using(settings.DATABASE_REPLICA).filter(pk=kwargs['subevent'], active=True).first()
+                if not self.subevent or not self.subevent.seating_plan:
+                    raise Http404()
+                return super().get(request, *args, **kwargs)
+            else:
+                raise Http404()
+        else:
+            if 'subevent' in kwargs or not request.event.seating_plan:
+                raise Http404()
+            else:
+                return super().get(request, *args, **kwargs)
+
+    def get_context_data(self, **kwargs):
+        context = super().get_context_data(**kwargs)
+        context['cart_redirect'] = eventreverse(self.request.event, 'presale:event.checkout.start',
+                                                kwargs={'cart_namespace': kwargs.get('cart_namespace') or ''})
+        if context['cart_redirect'].startswith('https:'):
+            context['cart_redirect'] = '/' + context['cart_redirect'].split('/', 3)[3]
+        return context
+
+
 class EventIcalDownload(EventViewMixin, View):
    def get(self, request, *args, **kwargs):
        if not self.request.event:
--- a/src/pretix/presale/views/widget.py
+++ b/src/pretix/presale/views/widget.py
@@ -515,6 +515,8 @@ class WidgetAPIProductList(EventListMixin, View):
            data['display_add_to_cart'] = False
            data['itemnum'] = 0

+        data['has_seating_plan'] = ev.seating_plan is not None
+
        vouchers_exist = self.request.event.get_cache().get('vouchers_exist')
        if vouchers_exist is None:
            vouchers_exist = self.request.event.vouchers.exists()
--- a/src/pretix/static/pretixbase/scss/_theme.scss
+++ b/src/pretix/static/pretixbase/scss/_theme.scss
@@ -1,6 +1,13 @@
 .sidebar-nav li > a > .fa {
  color: $navbar-inverse-bg;
 }
+.sidebar-nav li > a > svg {
+  position: relative;
+  top: 3px;
+  path {
+    fill: $navbar-inverse-bg;
+  }
+}
 .nav .testmode a {
  background: $brand-warning;
  color: black;
@@ -168,6 +175,11 @@
  border: 1px solid #ddd;
 }

+svg.svg-icon {
+  position: relative;
+  top: 2px;
+}
+
@include table-row-variant('success', lighten($brand-success, 40%));
@include table-row-variant('info', lighten($brand-info, 30%));
@include table-row-variant('warning', lighten($brand-warning, 40%));
--- a/src/pretix/static/pretixcontrol/js/ui/orderchange.js
+++ b/src/pretix/static/pretixcontrol/js/ui/orderchange.js
@@ -46,6 +46,58 @@ $(function () {
            );
        };
        $itemvar.on("change", update_price);
-        $subevent.on("change", update_price);
+        $subevent.on("change", update_price).on("change", function () {
+            var seat = $(this).closest(".form-order-change").find("[id$=seat]");
+            if (seat.length) {
+                seat.prop("required", !!$subevent.val());
+            }
+        });
+    });
+    $('[data-model-select2=seat]').each(function () {
+        var $s = $(this);
+        $s.select2({
+            theme: "bootstrap",
+            delay: 100,
+            allowClear: !$s.prop("required"),
+            width: '100%',
+            language: $("body").attr("data-select2-locale"),
+            placeholder: $(this).attr("data-placeholder"),
+            ajax: {
+                url: function() {
+                    var se = $(this).closest(".form-order-change, .form-horizontal").attr("data-subevent");
+                    var url = $(this).attr('data-select2-url');
+                    var changed = $(this).closest(".form-order-change, .form-horizontal").find("[id$=subevent]").val();
+                    if (changed) {
+                        return url + '?subevent=' + changed;
+                    } else if (se) {
+                        return url + '?subevent=' + se;
+                    } else {
+                        return url;
+                    }
+                },
+                data: function (params) {
+                    return {
+                        query: params.term,
+                        page: params.page || 1
+                    }
+                }
+            },
+            templateResult: function (res) {
+                if (!res.id) {
+                    return res.text;
+                }
+                var $ret = $("<span>").append(
+                    $("<span>").addClass("primary").append($("<div>").text(res.text).html())
+                );
+                if (res.event) {
+                    $ret.append(
+                        $("<span>").addClass("secondary").append(
+                            $("<span>").addClass("fa fa-calendar fa-fw")
+                        ).append(" ").append($("<div>").text(res.event).html())
+                    );
+                }
+                return $ret;
+            },
+        });
    });
 });
--- a/src/pretix/static/pretixpresale/js/ui/main.js
+++ b/src/pretix/static/pretixpresale/js/ui/main.js
@@ -197,6 +197,11 @@ $(function () {
                    is_enabled = true;
                }
            });
+            $(".input-seat-selection option").each(function() {
+                if ($(this).val() && $(this).val() !== "" && $(this).prop('selected')) {
+                    is_enabled = true;
+                }
+            });
        }
        if (!is_enabled) {
            $("#btn-add-to-cart").prop("disabled", !is_enabled).popover({'content': gettext("Please enter a quantity for one of the ticket types."), 'placement': 'top', 'trigger': 'hover focus'});
@@ -205,7 +210,8 @@ $(function () {
        }
    };
    update_cart_form();
-    $(".product-row input[type=checkbox], .variations input[type=checkbox], .product-row input[type=radio], .variations input[type=radio], .input-item-count").on("change mouseup keyup", update_cart_form);
+    $(".product-row input[type=checkbox], .variations input[type=checkbox], .product-row input[type=radio], .variations input[type=radio], .input-item-count, .input-seat-selection")
+        .on("change mouseup keyup", update_cart_form);

    $(".table-calendar td.has-events").click(function () {
        var $tr = $(this).closest(".table-calendar").find(".selected-day");
--- a/src/pretix/static/pretixpresale/js/widget/widget.js
+++ b/src/pretix/static/pretixpresale/js/widget/widget.js
@@ -44,6 +44,7 @@ var strings = {
    'back': django.pgettext('widget', 'Back'),
    'next_month': django.pgettext('widget', 'Next month'),
    'previous_month': django.pgettext('widget', 'Previous month'),
+    'show_seating': django.pgettext('widget', 'Open seat selection'),
    'days': {
        'MO': django.gettext('Mo'),
        'TU': django.gettext('Tu'),
@@ -557,6 +558,26 @@ var shared_methods = {
            window.open(redirect_url);
        }
    },
+    startseating: function () {
+        var redirect_url = this.$root.target_url + 'w/' + widget_id;
+        if (this.$root.subevent){
+            redirect_url += '/' + this.$root.subevent;
+        }
+        redirect_url += '/seatingframe/?iframe=1&locale=' + lang;
+        if (this.$root.cart_id) {
+            redirect_url += '&take_cart_id=' + this.$root.cart_id;
+        }
+        if (this.$root.widget_data) {
+            redirect_url += '&widget_data=' + escape(this.$root.widget_data_json);
+        }
+        if (this.$root.useIframe) {
+            var iframe = this.$root.overlay.$children[0].$refs['frame-container'].children[0];
+            this.$root.overlay.frame_loading = true;
+            iframe.src = redirect_url;
+        } else {
+            window.open(redirect_url);
+        }
+    },
    handleResize: function () {
        this.mobile = this.$refs.wrapper.clientWidth <= 800;
    }
@@ -678,6 +699,11 @@ Vue.component('pretix-widget-event-form', {
        + strings['cart_exists']
        + '<div class="pretix-widget-clear"></div>'
        + '</div>'
+        + '<div class="pretix-widget-seating-link-wrapper" v-if="this.$root.has_seating_plan">'
+        + '<button class="pretix-widget-seating-link" @click.prevent="$parent.startseating">'
+        + strings['show_seating']
+        + '</button>'
+        + '</div>'
        + '<category v-for="category in this.$root.categories" :category="category" :key="category.id"></category>'
        + '<div class="pretix-widget-action" v-if="$root.display_add_to_cart">'
        + '<button @click="$parent.buy" type="submit">' + strings.buy + '</button>'
@@ -1061,6 +1087,7 @@ var shared_root_methods = {
                root.cart_id = cart_id;
                root.cart_exists = data.cart_exists;
                root.vouchers_exist = data.vouchers_exist;
+                root.has_seating_plan = data.has_seating_plan;
                root.itemnum = data.itemnum;
            }
            if (root.loading > 0) {
@@ -1226,7 +1253,8 @@ var create_widget = function (element) {
                disable_vouchers: disable_vouchers,
                cart_exists: false,
                itemcount: 0,
-                overlay: null
+                overlay: null,
+                has_seating_plan: false
            }
        },
        created: function () {
--- a/src/pretix/static/pretixpresale/scss/widget.scss
+++ b/src/pretix/static/pretixpresale/scss/widget.scss
@@ -478,6 +478,15 @@
      font-weight: bold;
    }
  }
+
+  .pretix-widget-seating-link-wrapper {
+    padding: 0 15px;
+    margin: 15px 0 10px;
+  }
+  .pretix-widget-seating-link {
+    display: block;
+    width: 100%;
+  }
 }

@keyframes pretix-widget-bounce-in {
--- a/src/pretix/static/seating/seating-plan.schema.json
+++ b/src/pretix/static/seating/seating-plan.schema.json
@@ -0,0 +1,225 @@
+{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "version": "0.0.1",
+  "title": "Seating Plan",
+  "description": "Seating plan for venues",
+  "type": "object",
+  "properties": {
+    "name": {
+      "type": "string"
+    },
+    "zones": {
+      "type": "array",
+      "description": "List of zones",
+      "items": { "$ref": "#/definitions/zone" }
+    },
+    "categories": {
+      "type": "array",
+      "description": "List of categories",
+      "items": { "$ref": "#/definitions/category" }
+    },
+    "size": {
+      "type": "object",
+      "description": "Size of the entire plan (in pixels)",
+      "properties": {
+        "width": { "type": "integer" },
+        "height": { "type": "integer" }
+      },
+      "required": ["width", "height"],
+      "additionalProperties": false
+    }
+  },
+  "required": ["zones", "name", "categories"],
+  "additionalProperties": false,
+  "definitions": {
+    "zone": {
+      "type": "object",
+      "description": "Zone represents the parent entity that groups all other entities. The zone itself can be hidden or displayed. Examples of different zones would be 'main area', 'balcony', etc.",
+      "properties": {
+        "name": {
+          "type": "string",
+          "description": "Name of the zone"
+        },
+        "displayed": {
+          "type": "boolean",
+          "description": "Should the zone outlines be displayed or not?"
+        },
+        "position": { "$ref": "#/definitions/position" },
+        "rows": {
+          "type": "array",
+          "description": "List of rows",
+          "items": { "$ref": "#/definitions/row" }
+        },
+        "areas": {
+          "type": "array",
+          "description": "List of areas",
+          "items": { "$ref": "#/definitions/area" }
+        },
+        "row_number_position": {
+          "type": ["string", "null"],
+          "enum": ["left", "right", null],
+          "description": "Should the row numbers be hidden?"
+        }
+      },
+      "required": ["position", "rows"],
+      "additionalProperties": false
+    },
+    "row": {
+      "type": "object",
+      "description": "Row is simply a collection of seats with some additional information that simplifies working with seats.",
+      "$comment": "Might need more (editor) infromation like direction, angle, curvature",
+      "properties": {
+        "row_number": {
+          "type": "string",
+          "description": "Row number or name by which it can be identified"
+        },
+        "seats": {
+          "type": "array",
+          "description": "List of seats in this row",
+          "items": { "$ref": "#/definitions/seat" }
+        },
+        "number_of_seats": {
+          "type": "integer",
+          "$comment": "This property might be redundant. Since the seats are nested within the row, it's easy to just count them."
+        },
+        "seats_spacing": {
+          "type": "integer",
+          "description": "How far apart should the seats be positioned?"
+        },
+        "row_number_position": {
+          "type": ["string", "null"],
+          "enum": ["left", "right", null],
+          "description": "Should the row numbers be hidden? (Overrides the zone setting)"
+        },
+        "position": {
+          "$ref": "#/definitions/position"
+        }
+      },
+      "required": ["seats", "row_number"],
+      "additionalProperties": false
+    },
+    "seat": {
+      "type": "object",
+      "description": "Individual seat that can be reserved.",
+      "properties": {
+        "seat_guid": {
+          "type": "string",
+          "description": "Seat global ID by which it can be identified. It should be globally unique (not just per row). It doesn't have to be pretty since it won't be shown to the user."
+        },
+        "seat_number": {
+          "type": "string",
+          "description": "Human-readable seat number."
+        },
+        "position": { "$ref": "#/definitions/position" },
+        "category": {
+          "type": "string",
+          "description": "What category does this seat belong to? This needs to refer to the name of a category defined on the top level of the file. Keep in mind that there is no way to enfore this requirement with this version of JSON schema."
+        }
+      },
+      "required": ["seat_guid", "seat_number", "position", "category"],
+      "additionalProperties": false
+    },
+    "area": {
+      "type": "object",
+      "description": "Area can represent anything from general admission area, to stage, bar or even tables.",
+      "$comment": "TODO needs a definition: should it be defined with parameters or with a free-form svg?",
+      "properties": {
+        "color": { "type": "string" },
+        "border_color": { "type": "string" },
+        "rotation": { "type": "number" },
+        "position": {
+          "$ref": "#/definitions/position"
+        },
+        "shape": {
+          "type": "string",
+          "enum": ["polygon", "rectangle", "ellipse", "circle", "text"]
+        },
+        "polygon": {
+          "type": "object",
+          "properties": {
+            "points": {
+              "type": "array",
+              "items": { "$ref": "#/definitions/position" }
+            }
+          },
+          "required": ["points"],
+          "additionalProperties": false
+        },
+        "rectangle": {
+          "type": "object",
+          "properties": {
+            "width": {
+              "type": "integer"
+            },
+            "height": {
+              "type": "integer"
+            }
+          },
+          "required": ["width", "height"],
+          "additionalProperties": false
+        },
+        "ellipse": {
+          "type": "object",
+          "properties": {
+            "radius": { "$ref": "#/definitions/position" }
+          },
+          "required": ["radius"],
+          "additionalProperties": false
+        },
+        "circle": {
+          "type": "object",
+          "properties": {
+            "radius": {
+              "type": "integer"
+            }
+          },
+          "required": ["radius"],
+          "additionalProperties": false
+        },
+        "text": {
+          "type": "object",
+          "properties": {
+            "text": { "type": "string" },
+            "color": { "type": "string" },
+            "position": {
+              "$ref": "#/definitions/position"
+            }
+          },
+          "required": ["text", "position"],
+          "additionalProperties": false
+        }
+      },
+      "additionalProperties": false
+    },
+    "position": {
+      "type": "object",
+      "description": "Position of the element",
+      "properties": {
+        "x": {
+          "type": "integer"
+        },
+        "y": {
+          "type": "integer"
+        }
+      },
+      "required": ["x", "y"],
+      "additionalProperties": false
+    },
+    "category": {
+      "type": "object",
+      "description": "A category of seats, e.g. a price level.",
+      "properties": {
+        "name": {
+          "type": "string",
+          "description": "Internal name of the seats, e.g. 'stalls'. This should be used to map this to actual shop products."
+        },
+        "color": {
+          "type": "string",
+          "description": "The color used to draw seats of this category."
+        }
+      },
+      "required": ["name"],
+      "additionalProperties": false
+    }
+  }
+}