API: Allow to simulate check-ins

doc/api/resources/checkin.rst

@@ -71,6 +71,8 @@ Checking a ticket in
    :>json object questions: List of questions to be answered for check-in, only set on status ``"incomplete"``.
    :>json object media_policy: Reusable media policy (see documentation on items), only set on status ``"exchange"``.
    :>json object media_type: Reusable media type (see documentation on items), only set on status ``"exchange"``.
+   :>json boolean simulate: Do not actually perform the check-in, only simulate the response. The ``position`` response
+                            object will not reflect the simulated changes.
 
    **Example request**:
 

src/pretix/api/serializers/checkin.py

@@ -90,6 +90,7 @@ class CheckinRPCRedeemInputSerializer(serializers.Serializer):
     answers = serializers.JSONField(required=False, allow_null=True)
     exchange_medium_type = serializers.ChoiceField(required=False, choices=MEDIA_TYPES)
     exchange_medium_identifier = serializers.CharField(required=False)
+    simulate = serializers.BooleanField(default=False, required=False)
 
     def __init__(self, *args, **kwargs):
         super().__init__(*args, **kwargs)

src/pretix/api/views/checkin.py

@@ -837,6 +837,11 @@ def _redeem_process(*, checkinlists, raw_barcode, answers_data, datetime, force,
             )
 
             if exchange_medium_identifier:  # other fields are filled, see CheckinRPCRedeemInputSerializer.validate
+                if simulate:
+                    raise CheckInError(
+                        gettext('You cannot simulate a medium exchange.'),
+                        'error'
+                    )
                 with transaction.atomic():
                     # Do exchange and check-in atomically, i.e. both succeed or both fail
                     medium = perform_media_exchange(
@@ -1064,6 +1069,7 @@ class CheckinRPCRedeemView(views.APIView):
             legacy_url_support=False,
             exchange_medium_type=s.validated_data.get('exchange_medium_type'),
             exchange_medium_identifier=s.validated_data.get('exchange_medium_identifier'),
+            simulate=s.validated_data.get('simulate'),
         )
 
 

src/pretix/base/migrations/0302_resolve_duplicate_codes_and_secrets.py

@@ -1,58 +0,0 @@
-# Generated by Django 4.2.8 on 2024-07-01 09:27
-import logging
-
-from django.db import migrations
-from django.db.models import Count
-
-logger = logging.getLogger(__name__)
-
-
-def clean_duplicate_secrets(apps, schema_editor):
-    # This will autofix all possible duplicate Order.code and OrderPosition.secret values,
-    # unless Order.code is already too long to append something. This would need to be fixed by
-    # sysadmins manually.
-    OrderPosition = apps.get_model("pretixbase", "OrderPosition")
-    Order = apps.get_model("pretixbase", "Order")
-
-    qs = OrderPosition.all.values("secret", "order__event__organizer_id").order_by().annotate(c=Count("*")).filter(c__gt=1)
-    for row in qs:
-        affected = OrderPosition.all.filter(
-            **{k: v for k, v in row.items() if k != "c"}
-        ).order_by("pk")
-        logger.error(f"Found {row['c']} tickets with with the same secret \"{row['secret']}\" in organizer {row['order__event__organizer_id']}, all except one will be changed")
-        for i, a in enumerate(affected):
-            if i > 0:
-                a.secret = a.secret + "__dupl__" + str(a.pk)
-                logger.info(
-                    f"Ticket {a.pk} has new secret {a.secret}"
-                )
-            a.save(update_fields=["organizer_id", "secret"])
-
-    qs = Order.objects.values("code", "event__organizer_id").order_by().annotate(c=Count("*")).filter(c__gt=1)
-    for row in qs:
-        affected = Order.objects.filter(
-            **{k: v for k, v in row.items() if k != "c"}
-        ).order_by("pk")
-        logger.error(f"Found {row['c']} orders with with the same code \"{row['code']}\" in organizer {row['event__organizer_id']}, all except one will be changed")
-        for i, a in enumerate(affected):
-            if i > 0:
-                if len(a.code) > 16 - len(str(a.pk)):
-                    raise ValueError(f"Cannot auto-fix order with duplicate code {a.code}, order code is too long already")
-                a.code = a.code + str(a.pk).zfill(16 - len(a.code))
-                logger.info(
-                    f"Order {a.pk} has new code {a.code}"
-                )
-            a.save(update_fields=["organizer_id", "code"])
-
-
-class Migration(migrations.Migration):
-    dependencies = [
-        (
-            "pretixbase",
-            "0301_reusablemedium_remove_orderposition",
-        ),
-    ]
-
-    operations = [
-        migrations.RunPython(clean_duplicate_secrets, migrations.RunPython.noop),
-    ]

src/pretix/base/migrations/0303_alter_order_organizer_alter_orderposition_organizer.py

@@ -1,46 +0,0 @@
-# Generated by Django 4.2.8 on 2024-07-01 09:27
-
-import django.db.models.deletion
-from django.db import migrations, models
-
-
-class Migration(migrations.Migration):
-    dependencies = [
-        (
-            "pretixbase",
-            "0302_resolve_duplicate_codes_and_secrets",
-        ),
-    ]
-
-    operations = [
-        migrations.RunSQL(
-            "UPDATE pretixbase_order "
-            "SET organizer_id = (SELECT e.organizer_id FROM pretixbase_event e WHERE e.id = pretixbase_order.event_id) "
-            "WHERE pretixbase_order.organizer_id IS NULL;",
-            migrations.RunSQL.noop,
-        ),
-        migrations.RunSQL(
-            "UPDATE pretixbase_orderposition "
-            "SET organizer_id = (SELECT e.organizer_id FROM pretixbase_order o LEFT JOIN pretixbase_event e ON e.id = o.event_id WHERE o.id = pretixbase_orderposition.order_id) "
-            "WHERE pretixbase_orderposition.organizer_id IS NULL;",
-            migrations.RunSQL.noop,
-        ),
-        migrations.AlterField(
-            model_name="order",
-            name="organizer",
-            field=models.ForeignKey(
-                on_delete=django.db.models.deletion.CASCADE,
-                related_name="orders",
-                to="pretixbase.organizer",
-            ),
-        ),
-        migrations.AlterField(
-            model_name="orderposition",
-            name="organizer",
-            field=models.ForeignKey(
-                on_delete=django.db.models.deletion.CASCADE,
-                related_name="order_positions",
-                to="pretixbase.organizer",
-            ),
-        ),
-    ]

src/pretix/base/models/orders.py

@@ -224,6 +224,8 @@ class Order(LockModel, LoggedModel):
         "Organizer",
         related_name="orders",
         on_delete=models.CASCADE,
+        null=True,
+        blank=True,
     )
     event = models.ForeignKey(
         Event,
@@ -327,7 +329,7 @@ class Order(LockModel, LoggedModel):
         default="line",
     )
 
-    objects = ScopedManager(OrderQuerySet.as_manager().__class__, organizer='organizer')
+    objects = ScopedManager(OrderQuerySet.as_manager().__class__, organizer='event__organizer')
 
     class Meta:
         verbose_name = _("Order")
@@ -2539,6 +2541,8 @@ class OrderPosition(AbstractPosition):
         "Organizer",
         related_name="order_positions",
         on_delete=models.CASCADE,
+        null=True,
+        blank=True,
     )
     order = models.ForeignKey(
         Order,
@@ -2595,7 +2599,7 @@ class OrderPosition(AbstractPosition):
         blank=True,
     )
 
-    all = ScopedManager(organizer='organizer')
+    all = ScopedManager(organizer='order__event__organizer')
     objects = ActivePositionManager()
 
     def __init__(self, *args, **kwargs):

src/pretix/base/services/checkin.py

@@ -40,7 +40,7 @@ import dateutil
 import dateutil.parser
 from dateutil.tz import datetime_exists
 from django.core.files import File
-from django.db import IntegrityError, transaction
+from django.db import IntegrityError
 from django.db.models import (
     BooleanField, Case, Count, ExpressionWrapper, F, IntegerField, Max, Min,
     OuterRef, Q, Subquery, TextField, Value, When,
@@ -59,6 +59,7 @@ from pretix.base.models import (
 )
 from pretix.base.signals import checkin_created, periodic_task
 from pretix.helpers import OF_SELF
+from pretix.helpers.database import conditional_atomic
 from pretix.helpers.jsonlogic import Logic
 from pretix.helpers.jsonlogic_boolalg import convert_to_dnf
 from pretix.helpers.jsonlogic_query import (
@@ -1043,10 +1044,10 @@ def perform_checkin(op: OrderPosition, clist: CheckinList, given_answers: dict,
         if not simulate:
             _save_answers(op, answers, given_answers)
 
-    with transaction.atomic():
+    with conditional_atomic(not simulate):
         # Lock order positions, if it is an entry. We don't need it for exits, as a race condition wouldn't be problematic
         opqs = OrderPosition.all.select_related("order", "item")
-        if type != Checkin.TYPE_EXIT:
+        if type != Checkin.TYPE_EXIT and not simulate:
             opqs = opqs.select_for_update(of=OF_SELF)
         op = opqs.get(pk=op.pk)
 

src/pretix/helpers/database.py

@@ -285,3 +285,12 @@ def get_deterministic_ordering(model, ordering):
             # on the primary key to provide total ordering.
             ordering.append("-pk")
     return ordering
+
+
+@contextlib.contextmanager
+def conditional_atomic(do_atomic, **kwargs):
+    if do_atomic:
+        with transaction.atomic(**kwargs):
+            yield
+    else:
+        yield

src/tests/api/test_checkinrpc.py

@@ -25,6 +25,7 @@ from unittest import mock
 
 import pytest
 from django.core.files.base import ContentFile
+from django.db import connection
 from django.utils.timezone import now
 from django_countries.fields import Country
 from django_scopes import scopes_disabled
@@ -36,6 +37,7 @@ from pretix.api.serializers.item import QuestionSerializer
 from pretix.base.models import (
     Checkin, InvoiceAddress, Item, Order, OrderPosition, ReusableMedium,
 )
+from pretix.testutils.db import readonly_db
 
 # Lots of this code is overlapping with test_checkin.py, and some of it is arguably redundant since it's triggering
 # the same backend code paths (for now). However, this is SUCH a critical part of pretix that we don't want to take
@@ -1739,3 +1741,41 @@ def test_exchange_create_gift_card(token_client, organizer, clist, event, order,
     with scopes_disabled():
         rm = ReusableMedium.objects.get(identifier="0412345")
         assert rm.linked_giftcard.currency == "EUR"
+
+
+@pytest.mark.django_db
+def test_simulate(token_client, organizer, clist, event, order):
+    with scopes_disabled():
+        p = order.positions.first()
+    with connection.execute_wrapper(readonly_db):
+        resp = _redeem(token_client, organizer, clist, p.secret, {"simulate": True})
+    assert resp.status_code == 201
+    assert resp.data['status'] == 'ok'
+    with scopes_disabled():
+        assert not p.checkins.exists()
+
+
+@pytest.mark.django_db
+def test_simulate_no_exchange(token_client, organizer, clist, event, order, item):
+    organizer.settings.reusable_media_type_nfc_uid = True
+    item.media_type = "nfc_uid"
+    item.media_policy = Item.MEDIA_POLICY_NEW
+    item.save()
+    with scopes_disabled():
+        rm = ReusableMedium.objects.create(
+            type="nfc_uid",
+            identifier="12345678",
+            organizer=organizer,
+        )
+    with connection.execute_wrapper(readonly_db):
+        resp = _redeem(token_client, organizer, clist, "z3fsn8jyufm5kpk768q69gkbyr5f4h6w", {
+            "source_type": "barcode",
+            "exchange_medium_type": "nfc_uid",
+            "exchange_medium_identifier": "12345678",
+            "simulate": True,
+        })
+    assert resp.status_code == 400
+    assert resp.data['status'] == 'error'
+    assert resp.data['reason'] == 'error'
+    with scopes_disabled():
+        assert not rm.linked_orderpositions.exists()