Fix annotated check-in list query

src/pretix/base/models/checkin.py

@@ -17,7 +17,18 @@ class CheckinList(LoggedModel):
 
     @staticmethod
     def annotate_with_numbers(qs, event):
-        from . import Order, OrderPosition
+        """
+        Modifies a queryset of checkin lists by annotating it with the number of order positions and
+        checkins associated with it.
+        """
+        # Import here to prevent circular import
+        from . import Order, OrderPosition, Item
+
+        # This is the mother of all subqueries. Sorry. I try to explain it, at least?
+        # First, we prepare a subquery that for every check-in that belongs to a paid-order
+        # position and to the list in question. Then, we check that it also belongs to the
+        # correct subevent (just to be sure) and aggregate over lists (so, over everything,
+        # since we filtered by lists).
         cqs = Checkin.objects.filter(
             position__order__event=event,
             position__order__status=Order.STATUS_PAID,
@@ -30,6 +41,11 @@ class CheckinList(LoggedModel):
         ).order_by().values('list').annotate(
             c=Count('*')
         ).values('c')
+
+        # Now for the hard part: getting all order positions that contribute to this list. This
+        # requires us to use TWO subqueries. The first one, pqs_all, will only be used for check-in
+        # lists that contain all the products of the event. This is the simpler one, it basically
+        # looks like the check-in counter above.
         pqs_all = OrderPosition.objects.filter(
             order__event=event,
             order__status=Order.STATUS_PAID,
@@ -41,10 +57,16 @@ class CheckinList(LoggedModel):
         ).order_by().values('order__event').annotate(
             c=Count('*')
         ).values('c')
+
+        # Now we need a subquery for the case of checkin lists that are limited to certain
+        # products. We cannot use OuterRef("limit_products") since that would do a cross-product
+        # with the products table and we'd get duplicate rows in the output with different annotations
+        # on them, which isn't useful at all. Therefore, we need to add a second layer of subqueries
+        # to retrieve all of those items and then check if the item_id is IN this subquery result.
         pqs_limited = OrderPosition.objects.filter(
             order__event=event,
             order__status=Order.STATUS_PAID,
-            item__in=OuterRef('limit_products')
+            item_id__in=Subquery(Item.objects.filter(checkinlist__pk=OuterRef(OuterRef('pk'))).values('pk'))
         ).filter(
             # This assumes that in an event with subevents, *all* positions have subevents
             # and *all* checkin lists have a subevent assigned
@@ -54,6 +76,9 @@ class CheckinList(LoggedModel):
             c=Count('*')
         ).values('c')
 
+        # Finally, we put all of this together. We force empty subquery aggregates to 0 by using Coalesce()
+        # and decide which subquery to use for this row. In the end, we compute an integer percentage in case
+        # we want to display a progress bar.
         return qs.annotate(
             checkin_count=Coalesce(Subquery(cqs, output_field=models.IntegerField()), 0),
             position_count=Coalesce(Case(

src/pretix/control/views/dashboards.py

@@ -192,14 +192,6 @@ def shop_state_widget(sender, **kwargs):
 
 @receiver(signal=event_dashboard_widgets)
 def checkin_widget(sender, subevent=None, **kwargs):
-    size_qs = OrderPosition.objects.filter(order__event=sender, order__status='p')
-    checked_qs = OrderPosition.objects.filter(order__event=sender, order__status='p', checkins__isnull=False)
-
-    # if this setting is False, we check only items for admission
-    if not sender.settings.ticket_download_nonadm:
-        size_qs = size_qs.filter(item__admission=True)
-        checked_qs = checked_qs.filter(item__admission=True)
-
     widgets = []
     qs = sender.checkin_lists.filter(subevent=subevent)
     qs = CheckinList.annotate_with_numbers(qs, sender)

src/tests/base/test_models.py

@@ -13,8 +13,9 @@ from django.test import TestCase
 from django.utils.timezone import now
 
 from pretix.base.models import (
-    CachedFile, CartPosition, Event, Item, ItemCategory, ItemVariation, Order,
+    CachedFile, CartPosition, CheckinList, Event, Item, ItemCategory,
-    OrderPosition, Organizer, Question, Quota, User, Voucher, WaitingListEntry,
+    ItemVariation, Order, OrderPosition, Organizer, Question, Quota, User,
+    Voucher, WaitingListEntry,
 )
 from pretix.base.models.event import SubEvent
 from pretix.base.models.items import SubEventItem, SubEventItemVariation
@@ -1066,3 +1067,66 @@ class CachedFileTestCase(TestCase):
             assert f.read().strip() == "file_content"
         cf.delete()
         assert not default_storage.exists(cf.file.name)
+
+
+class CheckinListTestCase(TestCase):
+    @classmethod
+    def setUpTestData(cls):
+        cls.organizer = Organizer.objects.create(name='Dummy', slug='dummy')
+        cls.event = Event.objects.create(
+            organizer=cls.organizer, name='Dummy', slug='dummy',
+            date_from=now(), date_to=now() - timedelta(hours=1),
+        )
+        cls.item1 = cls.event.items.create(name="Ticket", default_price=12)
+        cls.item2 = cls.event.items.create(name="Shirt", default_price=6)
+        cls.cl_all = cls.event.checkin_lists.create(
+            name='All', all_products=True
+        )
+        cls.cl_both = cls.event.checkin_lists.create(
+            name='Both', all_products=False
+        )
+        cls.cl_both.limit_products.add(cls.item1)
+        cls.cl_both.limit_products.add(cls.item2)
+        cls.cl_tickets = cls.event.checkin_lists.create(
+            name='Tickets', all_products=False
+        )
+        cls.cl_tickets.limit_products.add(cls.item1)
+        o = Order.objects.create(
+            code='FOO', event=cls.event, email='dummy@dummy.test',
+            status=Order.STATUS_PAID,
+            datetime=now(), expires=now() + timedelta(days=10),
+            total=Decimal("30"), payment_provider='banktransfer', locale='en'
+        )
+        OrderPosition.objects.create(
+            order=o,
+            item=cls.item1,
+            variation=None,
+            price=Decimal("12"),
+        )
+        op2 = OrderPosition.objects.create(
+            order=o,
+            item=cls.item1,
+            variation=None,
+            price=Decimal("12"),
+        )
+        op3 = OrderPosition.objects.create(
+            order=o,
+            item=cls.item2,
+            variation=None,
+            price=Decimal("6"),
+        )
+        op2.checkins.create(list=cls.cl_tickets)
+        op3.checkins.create(list=cls.cl_both)
+
+    def test_annotated(self):
+        lists = list(CheckinList.annotate_with_numbers(self.event.checkin_lists.order_by('name'), self.event))
+        assert lists == [self.cl_all, self.cl_both, self.cl_tickets]
+        assert lists[0].checkin_count == 0
+        assert lists[0].position_count == 3
+        assert lists[0].percent == 0
+        assert lists[1].checkin_count == 1
+        assert lists[1].position_count == 3
+        assert lists[1].percent == 33
+        assert lists[2].checkin_count == 1
+        assert lists[2].position_count == 2
+        assert lists[2].percent == 50