Reusable media (#3131)

Co-authored-by: Martin Gross <gross@rami.io>

src/pretix/api/auth/devicesecurity.py

@@ -81,6 +81,7 @@ class PretixScanSecurityProfile(AllowListSecurityProfile):
         ('POST', 'api-v1:upload'),
         ('POST', 'api-v1:checkinrpc.redeem'),
         ('GET', 'api-v1:checkinrpc.search'),
+        ('GET', 'api-v1:reusablemedium-list'),
     )
 
 
@@ -220,6 +221,7 @@ class PretixPosSecurityProfile(AllowListSecurityProfile):
         ('POST', 'api-v1:upload'),
         ('POST', 'api-v1:checkinrpc.redeem'),
         ('GET', 'api-v1:checkinrpc.search'),
+        ('POST', 'api-v1:reusablemedium-lookup'),
     )
 
 

src/pretix/api/serializers/checkin.py

@@ -26,6 +26,7 @@ from rest_framework.exceptions import ValidationError
 from pretix.api.serializers.event import SubEventSerializer
 from pretix.api.serializers.i18n import I18nAwareModelSerializer
 from pretix.base.channels import get_all_sales_channels
+from pretix.base.media import MEDIA_TYPES
 from pretix.base.models import Checkin, CheckinList
 
 
@@ -84,6 +85,7 @@ class CheckinRPCRedeemInputSerializer(serializers.Serializer):
     lists = serializers.PrimaryKeyRelatedField(required=True, many=True, queryset=CheckinList.objects.none())
     secret = serializers.CharField(required=True, allow_null=False)
     force = serializers.BooleanField(default=False, required=False)
+    source_type = serializers.ChoiceField(choices=[(k, v) for k, v in MEDIA_TYPES.items()], default='barcode')
     type = serializers.ChoiceField(choices=Checkin.CHECKIN_TYPES, default=Checkin.TYPE_ENTRY)
     ignore_unpaid = serializers.BooleanField(default=False, required=False)
     questions_supported = serializers.BooleanField(default=True, required=False)

src/pretix/api/serializers/event.py

@@ -797,6 +797,21 @@ class EventSettingsSerializer(SettingsSerializer):
         'logo_show_title',
         'og_image',
         'name_scheme',
+        'reusable_media_active',
+        'reusable_media_type_barcode',
+        'reusable_media_type_barcode_identifier_length',
+        'reusable_media_type_nfc_uid',
+        'reusable_media_type_nfc_uid_autocreate_giftcard',
+        'reusable_media_type_nfc_uid_autocreate_giftcard_currency',
+    ]
+    readonly_fields = [
+        # These are read-only since they are currently only settable on organizers, not events
+        'reusable_media_active',
+        'reusable_media_type_barcode',
+        'reusable_media_type_barcode_identifier_length',
+        'reusable_media_type_nfc_uid',
+        'reusable_media_type_nfc_uid_autocreate_giftcard',
+        'reusable_media_type_nfc_uid_autocreate_giftcard_currency',
     ]
 
     def __init__(self, *args, **kwargs):
@@ -863,6 +878,8 @@ class DeviceEventSettingsSerializer(EventSettingsSerializer):
         'invoice_address_from_tax_id',
         'invoice_address_from_vat_id',
         'name_scheme',
+        'reusable_media_type_barcode',
+        'reusable_media_type_nfc_uid',
         'system_question_order',
     ]
 

src/pretix/api/serializers/item.py

@@ -244,7 +244,8 @@ class ItemSerializer(I18nAwareModelSerializer):
                   'grant_membership_duration_like_event', 'grant_membership_duration_days',
                   'grant_membership_duration_months', 'validity_mode', 'validity_fixed_from', 'validity_fixed_until',
                   'validity_dynamic_duration_minutes', 'validity_dynamic_duration_hours', 'validity_dynamic_duration_days',
-                  'validity_dynamic_duration_months', 'validity_dynamic_start_choice', 'validity_dynamic_start_choice_day_limit')
+                  'validity_dynamic_duration_months', 'validity_dynamic_start_choice', 'validity_dynamic_start_choice_day_limit',
+                  'media_policy', 'media_type')
         read_only_fields = ('has_variations',)
 
     def __init__(self, *args, **kwargs):
@@ -263,6 +264,7 @@ class ItemSerializer(I18nAwareModelSerializer):
 
         Item.clean_per_order(data.get('min_per_order'), data.get('max_per_order'))
         Item.clean_available(data.get('available_from'), data.get('available_until'))
+        Item.clean_media_settings(self.context['event'], data.get('media_policy'), data.get('media_type'), data.get('issue_giftcard'))
 
         if data.get('personalized') and not data.get('admission'):
             raise ValidationError(_('Only admission products can currently be personalized.'))

src/pretix/api/serializers/media.py

@@ -0,0 +1,128 @@
+#
+# This file is part of pretix (Community Edition).
+#
+# Copyright (C) 2014-2020 Raphael Michel and contributors
+# Copyright (C) 2020-2021 rami.io GmbH and contributors
+#
+# This program is free software: you can redistribute it and/or modify it under the terms of the GNU Affero General
+# Public License as published by the Free Software Foundation in version 3 of the License.
+#
+# ADDITIONAL TERMS APPLY: Pursuant to Section 7 of the GNU Affero General Public License, additional terms are
+# applicable granting you additional permissions and placing additional restrictions on your usage of this software.
+# Please refer to the pretix LICENSE file to obtain the full terms applicable to this work. If you did not receive
+# this file, see <https://pretix.eu/about/en/license>.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied
+# warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Affero General Public License for more
+# details.
+#
+# You should have received a copy of the GNU Affero General Public License along with this program.  If not, see
+# <https://www.gnu.org/licenses/>.
+#
+import logging
+from decimal import Decimal
+
+from django.utils.translation import gettext_lazy as _
+from rest_framework import serializers
+from rest_framework.exceptions import ValidationError
+
+from pretix.api.serializers.i18n import I18nAwareModelSerializer
+from pretix.api.serializers.order import OrderPositionSerializer
+from pretix.api.serializers.organizer import (
+    CustomerSerializer, GiftCardSerializer,
+)
+from pretix.base.models import Order, OrderPosition, ReusableMedium
+
+logger = logging.getLogger(__name__)
+
+
+class NestedOrderMiniSerializer(I18nAwareModelSerializer):
+    event = serializers.SlugRelatedField(slug_field='slug', read_only=True)
+
+    class Meta:
+        model = Order
+        fields = ['code', 'event']
+
+
+class NestedOrderPositionSerializer(OrderPositionSerializer):
+    order = NestedOrderMiniSerializer()
+
+
+class NestedGiftCardSerializer(GiftCardSerializer):
+
+    def to_representation(self, instance):
+        d = super().to_representation(instance)
+        if hasattr(instance, 'cached_value'):
+            d['value'] = str(Decimal(instance.cached_value).quantize(Decimal("0.01")))
+        else:
+            d['value'] = str(Decimal(instance.value).quantize(Decimal("0.01")))
+        return d
+
+
+class ReusableMediaSerializer(I18nAwareModelSerializer):
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+
+        if 'linked_giftcard' in self.context['request'].query_params.getlist('expand'):
+            self.fields['linked_giftcard'] = NestedGiftCardSerializer(read_only=True)
+        else:
+            self.fields['linked_giftcard'] = serializers.PrimaryKeyRelatedField(
+                required=False,
+                allow_null=True,
+                queryset=self.context['organizer'].issued_gift_cards.all()
+            )
+
+        if 'linked_orderposition' in self.context['request'].query_params.getlist('expand'):
+            self.fields['linked_orderposition'] = NestedOrderPositionSerializer(read_only=True)
+        else:
+            self.fields['linked_orderposition'] = serializers.PrimaryKeyRelatedField(
+                required=False,
+                allow_null=True,
+                queryset=OrderPosition.all.filter(order__event__organizer=self.context['organizer']),
+            )
+
+        if 'customer' in self.context['request'].query_params.getlist('expand'):
+            self.fields['customer'] = CustomerSerializer(read_only=True)
+        else:
+            self.fields['customer'] = serializers.SlugRelatedField(
+                required=False,
+                allow_null=True,
+                slug_field='identifier',
+                queryset=self.context['organizer'].customers.all()
+            )
+
+    def validate(self, data):
+        data = super().validate(data)
+        if 'type' in data and 'identifier' in data:
+            qs = self.context['organizer'].reusable_media.filter(
+                identifier=data['identifier'], type=data['type']
+            )
+            if self.instance:
+                qs = qs.exclude(pk=self.instance.pk)
+            if qs.exists():
+                raise ValidationError(
+                    {'identifier': _('A medium with the same identifier and type already exists in your organizer account.')}
+                )
+        return data
+
+    class Meta:
+        model = ReusableMedium
+        fields = (
+            'id',
+            'created',
+            'updated',
+            'type',
+            'identifier',
+            'active',
+            'expires',
+            'customer',
+            'linked_orderposition',
+            'linked_giftcard',
+            'info',
+            'notes',
+        )
+
+
+class MediaLookupInputSerializer(serializers.Serializer):
+    type = serializers.CharField(required=True)
+    identifier = serializers.CharField(required=True)

src/pretix/api/serializers/order.py

@@ -33,6 +33,7 @@ from django.utils.encoding import force_str
 from django.utils.timezone import now
 from django.utils.translation import gettext_lazy
 from django_countries.fields import Country
+from django_scopes import scopes_disabled
 from rest_framework import serializers
 from rest_framework.exceptions import ValidationError
 from rest_framework.relations import SlugRelatedField
@@ -48,8 +49,8 @@ from pretix.base.decimal import round_decimal
 from pretix.base.i18n import language
 from pretix.base.models import (
     CachedFile, Checkin, Customer, Invoice, InvoiceAddress, InvoiceLine, Item,
-    ItemVariation, Order, OrderPosition, Question, QuestionAnswer, Seat,
-    SubEvent, TaxRule, Voucher,
+    ItemVariation, Order, OrderPosition, Question, QuestionAnswer,
+    ReusableMedium, Seat, SubEvent, TaxRule, Voucher,
 )
 from pretix.base.models.orders import (
     BlockedTicketSecret, CartPosition, OrderFee, OrderPayment, OrderRefund,
@@ -356,6 +357,9 @@ class PdfDataSerializer(serializers.Field):
     def to_representation(self, instance: OrderPosition):
         res = {}
 
+        if 'event' not in self.context:
+            return {}
+
         ev = instance.subevent or instance.order.event
         with language(instance.order.locale, instance.order.event.settings.region):
             # This needs to have some extra performance improvements to avoid creating hundreds of queries when
@@ -784,13 +788,15 @@ class OrderPositionCreateSerializer(I18nAwareModelSerializer):
                                            required=False, allow_null=True)
     country = CompatibleCountryField(source='*')
     requested_valid_from = serializers.DateTimeField(required=False, allow_null=True)
+    use_reusable_medium = serializers.PrimaryKeyRelatedField(queryset=ReusableMedium.objects.none(),
+                                                             required=False, allow_null=True)
 
     class Meta:
         model = OrderPosition
         fields = ('positionid', 'item', 'variation', 'price', 'attendee_name', 'attendee_name_parts', 'attendee_email',
                   'company', 'street', 'zipcode', 'city', 'country', 'state', 'is_bundled',
                   'secret', 'addon_to', 'subevent', 'answers', 'seat', 'voucher', 'valid_from', 'valid_until',
-                  'requested_valid_from')
+                  'requested_valid_from', 'use_reusable_medium')
 
     def __init__(self, *args, **kwargs):
         super().__init__(*args, **kwargs)
@@ -799,6 +805,9 @@ class OrderPositionCreateSerializer(I18nAwareModelSerializer):
                 v.required = False
                 v.allow_blank = True
                 v.allow_null = True
+        with scopes_disabled():
+            if 'use_reusable_medium' in self.fields:
+                self.fields['use_reusable_medium'].queryset = ReusableMedium.objects.all()
 
     def validate_secret(self, secret):
         if secret and OrderPosition.all.filter(order__event=self.context['event'], secret=secret).exists():
@@ -807,6 +816,13 @@ class OrderPositionCreateSerializer(I18nAwareModelSerializer):
             )
         return secret
 
+    def validate_use_reusable_medium(self, m):
+        if m.organizer_id != self.context['event'].organizer_id:
+            raise ValidationError(
+                'The specified medium does not belong to this organizer.'
+            )
+        return m
+
     def validate_item(self, item):
         if item.event != self.context['event']:
             raise ValidationError(
@@ -1264,7 +1280,7 @@ class OrderCreateSerializer(I18nAwareModelSerializer):
                     pos_data['attendee_name_parts'] = {
                         '_legacy': attendee_name
                     }
-                pos = OrderPosition(**{k: v for k, v in pos_data.items() if k != 'answers' and k != '_quotas'})
+                pos = OrderPosition(**{k: v for k, v in pos_data.items() if k != 'answers' and k != '_quotas' and k != 'use_reusable_medium'})
                 if simulate:
                     pos.order = order._wrapped
                 else:
@@ -1332,6 +1348,7 @@ class OrderCreateSerializer(I18nAwareModelSerializer):
             # Save instances
             for pos_data in positions_data:
                 answers_data = pos_data.pop('answers', [])
+                use_reusable_medium = pos_data.pop('use_reusable_medium', None)
                 pos = pos_data['__instance']
                 pos._calculate_tax()
 
@@ -1370,6 +1387,17 @@ class OrderCreateSerializer(I18nAwareModelSerializer):
                             answ = pos.answers.create(**answ_data)
                             answ.options.add(*options)
 
+                    if use_reusable_medium:
+                        use_reusable_medium.linked_orderposition = pos
+                        use_reusable_medium.save(update_fields=['linked_orderposition'])
+                        use_reusable_medium.log_action(
+                            'pretix.reusable_medium.linked_orderposition.changed',
+                            data={
+                                'by_order': order.code,
+                                'linked_orderposition': pos.pk,
+                            }
+                        )
+
             if not simulate:
                 for cp in delete_cps:
                     if cp.addon_to_id:

src/pretix/api/serializers/organizer.py

@@ -183,7 +183,7 @@ class TeamSerializer(serializers.ModelSerializer):
             'id', 'name', 'all_events', 'limit_events', 'can_create_events', 'can_change_teams',
             'can_change_organizer_settings', 'can_manage_gift_cards', 'can_change_event_settings',
             'can_change_items', 'can_view_orders', 'can_change_orders', 'can_view_vouchers',
-            'can_change_vouchers', 'can_checkin_orders', 'can_manage_customers'
+            'can_change_vouchers', 'can_checkin_orders', 'can_manage_customers', 'can_manage_reusable_media'
         )
 
     def validate(self, data):
@@ -333,6 +333,12 @@ class OrganizerSettingsSerializer(SettingsSerializer):
         'cookie_consent_dialog_text_secondary',
         'cookie_consent_dialog_button_yes',
         'cookie_consent_dialog_button_no',
+        'reusable_media_active',
+        'reusable_media_type_barcode',
+        'reusable_media_type_barcode_identifier_length',
+        'reusable_media_type_nfc_uid',
+        'reusable_media_type_nfc_uid_autocreate_giftcard',
+        'reusable_media_type_nfc_uid_autocreate_giftcard_currency',
     ]
 
     def __init__(self, *args, **kwargs):

src/pretix/api/serializers/settings.py

@@ -36,6 +36,7 @@ logger = logging.getLogger(__name__)
 
 class SettingsSerializer(serializers.Serializer):
     default_fields = []
+    readonly_fields = []
 
     def __init__(self, *args, **kwargs):
         self.changed_data = []
@@ -59,8 +60,13 @@ class SettingsSerializer(serializers.Serializer):
             f.parent = self
             self.fields[fname] = f
 
+    def validate(self, attrs):
+        return {k: v for k, v in attrs.items() if k not in self.readonly_fields}
+
     def update(self, instance: HierarkeyProxy, validated_data):
         for attr, value in validated_data.items():
+            if attr in self.readonly_fields:
+                continue
             if isinstance(value, FieldFile):
                 # Delete old file
                 fname = instance.get(attr, as_type=File)

src/pretix/api/urls.py

@@ -42,9 +42,9 @@ from rest_framework import routers
 from pretix.api.views import cart
 
 from .views import (
-    checkin, device, discount, event, exporters, idempotency, item, oauth,
-    order, organizer, shredders, upload, user, version, voucher, waitinglist,
-    webhooks,
+    checkin, device, discount, event, exporters, idempotency, item, media,
+    oauth, order, organizer, shredders, upload, user, version, voucher,
+    waitinglist, webhooks,
 )
 
 router = routers.DefaultRouter()
@@ -59,6 +59,7 @@ orga_router.register(r'giftcards', organizer.GiftCardViewSet)
 orga_router.register(r'customers', organizer.CustomerViewSet)
 orga_router.register(r'memberships', organizer.MembershipViewSet)
 orga_router.register(r'membershiptypes', organizer.MembershipTypeViewSet)
+orga_router.register(r'reusablemedia', media.ReusableMediaViewSet)
 orga_router.register(r'teams', organizer.TeamViewSet)
 orga_router.register(r'devices', organizer.DeviceViewSet)
 orga_router.register(r'exporters', exporters.OrganizerExportersViewSet, basename='exporters')

src/pretix/api/views/checkin.py

@@ -59,7 +59,7 @@ from pretix.api.views.order import OrderPositionFilter
 from pretix.base.i18n import language
 from pretix.base.models import (
     CachedFile, Checkin, CheckinList, Device, Event, Order, OrderPosition,
-    Question, RevokedTicketSecret, TeamAPIToken,
+    Question, ReusableMedium, RevokedTicketSecret, TeamAPIToken,
 )
 from pretix.base.services.checkin import (
     CheckInError, RequiredQuestionsError, SQLLogic, perform_checkin,
@@ -396,7 +396,7 @@ def _checkin_list_position_queryset(checkinlists, ignore_status=False, ignore_pr
 
 def _redeem_process(*, checkinlists, raw_barcode, answers_data, datetime, force, checkin_type, ignore_unpaid, nonce,
                     untrusted_input, user, auth, expand, pdf_data, request, questions_supported, canceled_supported,
-                    legacy_url_support=False):
+                    source_type='barcode', legacy_url_support=False):
     if not checkinlists:
         raise ValidationError('No check-in list passed.')
 
@@ -422,6 +422,7 @@ def _redeem_process(*, checkinlists, raw_barcode, answers_data, datetime, force,
 
     common_checkin_args = dict(
         raw_barcode=raw_barcode,
+        raw_source_type=source_type,
         type=checkin_type,
         list=checkinlists[0],
         datetime=datetime,
@@ -433,7 +434,7 @@ def _redeem_process(*, checkinlists, raw_barcode, answers_data, datetime, force,
     raw_barcode_for_checkin = None
     from_revoked_secret = False
 
-    # 1. Gather a list of positions that could be the one we looking fore, either from their ID, secret or
+    # 1. Gather a list of positions that could be the one we looking for, either from their ID, secret or
     #    parent secret
     queryset = _checkin_list_position_queryset(checkinlists, pdf_data=pdf_data, ignore_status=True, ignore_products=True).order_by(
         F('addon_to').asc(nulls_first=True)
@@ -457,98 +458,111 @@ def _redeem_process(*, checkinlists, raw_barcode, answers_data, datetime, force,
 
     # 2. Handle the "nothing found" case: Either it's really a bogus secret that we don't know (-> error), or it
     #    might be a revoked one that we actually know (-> error, but with better error message and logging and
-    #    with respecting the force option).
+    #    with respecting the force option), or it's a reusable medium (-> proceed with that)
     if not op_candidates:
-        revoked_matches = list(RevokedTicketSecret.objects.filter(event_id__in=list_by_event.keys(), secret=raw_barcode))
-        if len(revoked_matches) == 0:
-            checkinlists[0].event.log_action('pretix.event.checkin.unknown', data={
-                'datetime': datetime,
-                'type': checkin_type,
-                'list': checkinlists[0].pk,
-                'barcode': raw_barcode,
-                'searched_lists': [cl.pk for cl in checkinlists]
-            }, user=user, auth=auth)
+        try:
+            media = ReusableMedium.objects.select_related('linked_orderposition').active().get(
+                organizer_id=checkinlists[0].event.organizer_id,
+                type=source_type,
+                identifier=raw_barcode,
+                linked_orderposition__isnull=False,
+            )
+            raw_barcode_for_checkin = raw_barcode
+        except ReusableMedium.DoesNotExist:
+            revoked_matches = list(
+                RevokedTicketSecret.objects.filter(event_id__in=list_by_event.keys(), secret=raw_barcode))
+            if len(revoked_matches) == 0:
+                checkinlists[0].event.log_action('pretix.event.checkin.unknown', data={
+                    'datetime': datetime,
+                    'type': checkin_type,
+                    'list': checkinlists[0].pk,
+                    'barcode': raw_barcode,
+                    'searched_lists': [cl.pk for cl in checkinlists]
+                }, user=user, auth=auth)
 
-            for cl in checkinlists:
-                for k, s in cl.event.ticket_secret_generators.items():
+                for cl in checkinlists:
+                    for k, s in cl.event.ticket_secret_generators.items():
+                        try:
+                            parsed = s.parse_secret(raw_barcode)
+                            common_checkin_args.update({
+                                'raw_item': parsed.item,
+                                'raw_variation': parsed.variation,
+                                'raw_subevent': parsed.subevent,
+                            })
+                        except:
+                            pass
+
+                Checkin.objects.create(
+                    position=None,
+                    successful=False,
+                    error_reason=Checkin.REASON_INVALID,
+                    **common_checkin_args,
+                )
+
+                if force and legacy_url_support and isinstance(auth, Device):
+                    # There was a bug in libpretixsync: If you scanned a ticket in offline mode that was
+                    # valid at the time but no longer exists at time of upload, the device would retry to
+                    # upload the same scan over and over again. Since we can't update all devices quickly,
+                    # here's a dirty workaround to make it stop.
                     try:
-                        parsed = s.parse_secret(raw_barcode)
-                        common_checkin_args.update({
-                            'raw_item': parsed.item,
-                            'raw_variation': parsed.variation,
-                            'raw_subevent': parsed.subevent,
-                        })
-                    except:
+                        brand = auth.software_brand
+                        ver = parse(auth.software_version)
+                        legacy_mode = (
+                            (brand == 'pretixSCANPROXY' and ver < parse('0.0.3')) or
+                            (brand == 'pretixSCAN Android' and ver < parse('1.11.2')) or
+                            (brand == 'pretixSCAN' and ver < parse('1.11.2'))
+                        )
+                        if legacy_mode:
+                            return Response({
+                                'status': 'error',
+                                'reason': Checkin.REASON_ALREADY_REDEEMED,
+                                'reason_explanation': None,
+                                'require_attention': False,
+                                '__warning': 'Compatibility hack active due to detected old pretixSCAN version',
+                            }, status=400)
+                    except:  # we don't care e.g. about invalid version numbers
                         pass
 
-            Checkin.objects.create(
-                position=None,
-                successful=False,
-                error_reason=Checkin.REASON_INVALID,
-                **common_checkin_args,
-            )
-
-            if force and legacy_url_support and isinstance(auth, Device):
-                # There was a bug in libpretixsync: If you scanned a ticket in offline mode that was
-                # valid at the time but no longer exists at time of upload, the device would retry to
-                # upload the same scan over and over again. Since we can't update all devices quickly,
-                # here's a dirty workaround to make it stop.
-                try:
-                    brand = auth.software_brand
-                    ver = parse(auth.software_version)
-                    legacy_mode = (
-                        (brand == 'pretixSCANPROXY' and ver < parse('0.0.3')) or
-                        (brand == 'pretixSCAN Android' and ver < parse('1.11.2')) or
-                        (brand == 'pretixSCAN' and ver < parse('1.11.2'))
-                    )
-                    if legacy_mode:
-                        return Response({
-                            'status': 'error',
-                            'reason': Checkin.REASON_ALREADY_REDEEMED,
-                            'reason_explanation': None,
-                            'require_attention': False,
-                            '__warning': 'Compatibility hack active due to detected old pretixSCAN version',
-                        }, status=400)
-                except:  # we don't care e.g. about invalid version numbers
-                    pass
-
-            return Response({
-                'detail': 'Not found.',  # for backwards compatibility
-                'status': 'error',
-                'reason': Checkin.REASON_INVALID,
-                'reason_explanation': None,
-                'require_attention': False,
-                'list': MiniCheckinListSerializer(checkinlists[0]).data,
-            }, status=404)
-        elif revoked_matches and force:
-            op_candidates = [revoked_matches[0].position]
-            if list_by_event[revoked_matches[0].event_id].addon_match:
-                op_candidates += list(revoked_matches[0].position.addons.all())
-            raw_barcode_for_checkin = raw_barcode
-            from_revoked_secret = True
+                return Response({
+                    'detail': 'Not found.',  # for backwards compatibility
+                    'status': 'error',
+                    'reason': Checkin.REASON_INVALID,
+                    'reason_explanation': None,
+                    'require_attention': False,
+                    'list': MiniCheckinListSerializer(checkinlists[0]).data,
+                }, status=404)
+            elif revoked_matches and force:
+                op_candidates = [revoked_matches[0].position]
+                if list_by_event[revoked_matches[0].event_id].addon_match:
+                    op_candidates += list(revoked_matches[0].position.addons.all())
+                raw_barcode_for_checkin = raw_barcode_for_checkin or raw_barcode
+                from_revoked_secret = True
+            else:
+                op = revoked_matches[0].position
+                op.order.log_action('pretix.event.checkin.revoked', data={
+                    'datetime': datetime,
+                    'type': checkin_type,
+                    'list': list_by_event[revoked_matches[0].event_id].pk,
+                    'barcode': raw_barcode
+                }, user=user, auth=auth)
+                common_checkin_args['list'] = list_by_event[revoked_matches[0].event_id]
+                Checkin.objects.create(
+                    position=op,
+                    successful=False,
+                    error_reason=Checkin.REASON_REVOKED,
+                    **common_checkin_args
+                )
+                return Response({
+                    'status': 'error',
+                    'reason': Checkin.REASON_REVOKED,
+                    'reason_explanation': None,
+                    'require_attention': False,
+                    'position': CheckinListOrderPositionSerializer(op, context=_make_context(context, revoked_matches[
+                        0].event)).data,
+                    'list': MiniCheckinListSerializer(list_by_event[revoked_matches[0].event_id]).data,
+                }, status=400)
         else:
-            op = revoked_matches[0].position
-            op.order.log_action('pretix.event.checkin.revoked', data={
-                'datetime': datetime,
-                'type': checkin_type,
-                'list': list_by_event[revoked_matches[0].event_id].pk,
-                'barcode': raw_barcode
-            }, user=user, auth=auth)
-            common_checkin_args['list'] = list_by_event[revoked_matches[0].event_id]
-            Checkin.objects.create(
-                position=op,
-                successful=False,
-                error_reason=Checkin.REASON_REVOKED,
-                **common_checkin_args
-            )
-            return Response({
-                'status': 'error',
-                'reason': Checkin.REASON_REVOKED,
-                'reason_explanation': None,
-                'require_attention': False,
-                'position': CheckinListOrderPositionSerializer(op, context=_make_context(context, revoked_matches[0].event)).data,
-                'list': MiniCheckinListSerializer(list_by_event[revoked_matches[0].event_id]).data,
-            }, status=400)
+            op_candidates = [media.linked_orderposition] + list(media.linked_orderposition.addons.all())
 
     # 3. Handle the "multiple options found" case: Except for the unlikely case of a secret being also a valid primary
     #    key on the same list, we're probably dealing with the ``addon_match`` case here and need to figure out
@@ -634,6 +648,7 @@ def _redeem_process(*, checkinlists, raw_barcode, answers_data, datetime, force,
                 auth=auth,
                 type=checkin_type,
                 raw_barcode=raw_barcode_for_checkin,
+                raw_source_type=source_type,
                 from_revoked_secret=from_revoked_secret,
             )
         except RequiredQuestionsError as e:
@@ -812,6 +827,7 @@ class CheckinRPCRedeemView(views.APIView):
         return _redeem_process(
             checkinlists=s.validated_data['lists'],
             raw_barcode=s.validated_data['secret'],
+            source_type=s.validated_data['source_type'],
             answers_data=s.validated_data.get('answers'),
             datetime=s.validated_data.get('datetime') or now(),
             force=s.validated_data['force'],

src/pretix/api/views/event.py

@@ -542,7 +542,8 @@ class EventSettingsView(views.APIView):
                 fname: {
                     'value': s.data[fname],
                     'label': getattr(field, '_label', fname),
-                    'help_text': getattr(field, '_help_text', None)
+                    'help_text': getattr(field, '_help_text', None),
+                    'readonly': fname in s.readonly_fields,
                 } for fname, field in s.fields.items()
             })
         return Response(s.data)

src/pretix/api/views/media.py

@@ -0,0 +1,160 @@
+#
+# This file is part of pretix (Community Edition).
+#
+# Copyright (C) 2014-2020 Raphael Michel and contributors
+# Copyright (C) 2020-2021 rami.io GmbH and contributors
+#
+# This program is free software: you can redistribute it and/or modify it under the terms of the GNU Affero General
+# Public License as published by the Free Software Foundation in version 3 of the License.
+#
+# ADDITIONAL TERMS APPLY: Pursuant to Section 7 of the GNU Affero General Public License, additional terms are
+# applicable granting you additional permissions and placing additional restrictions on your usage of this software.
+# Please refer to the pretix LICENSE file to obtain the full terms applicable to this work. If you did not receive
+# this file, see <https://pretix.eu/about/en/license>.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied
+# warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Affero General Public License for more
+# details.
+#
+# You should have received a copy of the GNU Affero General Public License along with this program.  If not, see
+# <https://www.gnu.org/licenses/>.
+#
+from decimal import Decimal
+
+import django_filters
+from django.db import transaction
+from django.db.models import OuterRef, Prefetch, Subquery, Sum
+from django.db.models.functions import Coalesce
+from django.utils.timezone import now
+from django_filters.rest_framework import DjangoFilterBackend, FilterSet
+from django_scopes import scopes_disabled
+from rest_framework import viewsets, serializers
+from rest_framework.decorators import action
+from rest_framework.exceptions import MethodNotAllowed
+from rest_framework.filters import OrderingFilter
+from rest_framework.response import Response
+
+from pretix.api.serializers.media import (
+    MediaLookupInputSerializer, ReusableMediaSerializer,
+)
+from pretix.base.media import MEDIA_TYPES
+from pretix.base.models import (
+    Checkin, GiftCard, GiftCardTransaction, OrderPosition, ReusableMedium,
+)
+from pretix.helpers import OF_SELF
+from pretix.helpers.dicts import merge_dicts
+
+with scopes_disabled():
+    class ReusableMediumFilter(FilterSet):
+        identifier = django_filters.CharFilter(field_name='identifier')
+        type = django_filters.CharFilter(field_name='type')
+        customer = django_filters.CharFilter(field_name='customer__identifier')
+        updated_since = django_filters.IsoDateTimeFilter(field_name='updated', lookup_expr='gte')
+        created_since = django_filters.IsoDateTimeFilter(field_name='created', lookup_expr='gte')
+
+        class Meta:
+            model = ReusableMedium
+            fields = ['identifier', 'type', 'active', 'customer', 'linked_orderposition', 'linked_giftcard']
+
+
+class ReusableMediaViewSet(viewsets.ModelViewSet):
+    serializer_class = ReusableMediaSerializer
+    queryset = ReusableMedium.objects.none()
+    permission = 'can_manage_reusable_media'
+    write_permission = 'can_manage_reusable_media'
+    filter_backends = (DjangoFilterBackend, OrderingFilter)
+    ordering = ('-updated', '-id')
+    ordering_fields = ('created', 'updated', 'identifier', 'type', 'id')
+    filterset_class = ReusableMediumFilter
+
+    def get_queryset(self):
+        s = GiftCardTransaction.objects.filter(
+            card=OuterRef('pk')
+        ).order_by().values('card').annotate(s=Sum('value')).values('s')
+        return self.request.organizer.reusable_media.prefetch_related(
+            Prefetch(
+                'linked_orderposition',
+                queryset=OrderPosition.objects.select_related(
+                    'order', 'order__event', 'order__event__organizer', 'seat',
+                ).prefetch_related(
+                    Prefetch('checkins', queryset=Checkin.objects.all()),
+                    'answers', 'answers__options', 'answers__question',
+                )
+            ),
+            Prefetch(
+                'linked_giftcard',
+                queryset=GiftCard.objects.annotate(
+                    cached_value=Coalesce(Subquery(s), Decimal('0.00'))
+                )
+            )
+        )
+
+    def get_serializer_context(self):
+        ctx = super().get_serializer_context()
+        ctx['organizer'] = self.request.organizer
+        return ctx
+
+    @transaction.atomic()
+    def perform_create(self, serializer):
+        inst = serializer.save(organizer=self.request.organizer)
+        inst.log_action(
+            'pretix.reusable_medium.created',
+            user=self.request.user,
+            auth=self.request.auth,
+            data=merge_dicts(self.request.data, {'id': inst.pk})
+        )
+
+    @transaction.atomic()
+    def perform_update(self, serializer):
+        ReusableMedium.objects.select_for_update(of=OF_SELF).get(pk=self.get_object().pk)
+        inst = serializer.save(identifier=serializer.instance.identifier, type=serializer.instance.type)
+        inst.log_action(
+            'pretix.reusable_medium.changed',
+            user=self.request.user,
+            auth=self.request.auth,
+            data=self.request.data,
+        )
+        return inst
+
+    def perform_destroy(self, instance):
+        raise MethodNotAllowed("Media cannot be deleted.")
+
+    @action(methods=["POST"], detail=False)
+    def lookup(self, request, *args, **kwargs):
+        s = MediaLookupInputSerializer(
+            data=request.data,
+        )
+        s.is_valid(raise_exception=True)
+
+        try:
+            m = ReusableMedium.objects.get(
+                type=s.validated_data["type"],
+                identifier=s.validated_data["identifier"],
+                organizer=request.organizer,
+            )
+            s = self.get_serializer(m)
+            return Response({"result": s.data})
+        except ReusableMedium.DoesNotExist:
+            mt = MEDIA_TYPES.get(s.validated_data["type"])
+            if mt:
+                m = mt.handle_unknown(request.organizer, s.validated_data["identifier"], request.user, request.auth)
+                if m:
+                    s = self.get_serializer(m)
+                    return Response({"result": s.data})
+
+            return Response({"result": None})
+
+    @scopes_disabled()  # we are sure enough that get_queryset() is correct, so we save some perforamnce
+    def list(self, request, **kwargs):
+        date = serializers.DateTimeField().to_representation(now())
+        queryset = self.filter_queryset(self.get_queryset())
+
+        page = self.paginate_queryset(queryset)
+        if page is not None:
+            serializer = self.get_serializer(page, many=True)
+            resp = self.get_paginated_response(serializer.data)
+            resp['X-Page-Generated'] = date
+            return resp
+
+        serializer = self.get_serializer(queryset, many=True)
+        return Response(serializer.data, headers={'X-Page-Generated': date})

src/pretix/api/views/order.py

@@ -244,7 +244,8 @@ class OrderViewSet(viewsets.ModelViewSet):
                     Prefetch('subevent', queryset=self.request.event.subevents.prefetch_related(
                         Prefetch('meta_values', to_attr='meta_values_cached', queryset=SubEventMetaValue.objects.select_related('property'))
                     )),
-                    Prefetch('addons', opq.select_related('item', 'variation', 'seat'))
+                    Prefetch('addons', opq.select_related('item', 'variation', 'seat')),
+                    'linked_media',
                 ).select_related('seat', 'addon_to', 'addon_to__seat')
             )
         else:
@@ -639,13 +640,11 @@ class OrderViewSet(viewsets.ModelViewSet):
                 raise ValidationError(_('One of the selected products is not available in the selected country.'))
             send_mail = serializer._send_mail
             order = serializer.instance
+
             if not order.pk:
-                # Simulation
+                # Simulation -- exit here
                 serializer = SimulatedOrderSerializer(order, context=serializer.context)
                 return Response(serializer.data, status=status.HTTP_201_CREATED)
-            else:
-                prefetch_related_objects([order], self._positions_prefetch(request))
-                serializer = OrderSerializer(order, context=serializer.context)
 
             order.log_action(
                 'pretix.event.order.placed',
@@ -679,6 +678,10 @@ class OrderViewSet(viewsets.ModelViewSet):
             if gen_invoice:
                 invoice = generate_invoice(order, trigger_pdf=True)
 
+            # Refresh serializer only after running signals
+            prefetch_related_objects([order], self._positions_prefetch(request))
+            serializer = OrderSerializer(order, context=serializer.context)
+
             if send_mail:
                 free_flow = (
                     payment and order.total == Decimal('0.00') and order.status == Order.STATUS_PAID and
@@ -1005,6 +1008,7 @@ class OrderPositionViewSet(viewsets.ModelViewSet):
                     Prefetch('meta_values', to_attr='meta_values_cached',
                              queryset=SubEventMetaValue.objects.select_related('property'))
                 )),
+                'linked_media',
                 Prefetch('order', self.request.event.orders.select_related('invoice_address').prefetch_related(
                     Prefetch(
                         'positions',

src/pretix/api/views/organizer.py

@@ -457,7 +457,8 @@ class OrganizerSettingsView(views.APIView):
                 fname: {
                     'value': s.data[fname],
                     'label': getattr(field, '_label', fname),
-                    'help_text': getattr(field, '_help_text', None)
+                    'help_text': getattr(field, '_help_text', None),
+                    'readonly': fname in s.readonly_fields,
                 } for fname, field in s.fields.items()
             })
         return Response(s.data)