Quotas API: Allow to bulk-query availability

doc/api/resources/quotas.rst

@@ -28,12 +28,22 @@ closed                                boolean                    Whether the quo
                                                                  field).
 release_after_exit                    boolean                    Whether the quota regains capacity as soon as some tickets
                                                                  have been scanned at an exit.
+available                             boolean                    Whether this quota is available. Only returned if ``with_availability=true``
+                                                                 is set on the request. Do not rely on this value for critical operations, it may be
+                                                                 slightly out of date.
+available_number                      integer                    Number of available tickets. Only returned if ``with_availability=true``
+                                                                 is set on the request. Do not rely on this value for critical operations, it may be
+                                                                 slightly out of date. ``null`` means unlimited.
 ===================================== ========================== =======================================================
 
 .. versionchanged:: 3.10
 
    The attribute ``release_after_exit`` has been added.
 
+.. versionchanged:: 4.1
+
+    The ``with_availability`` query parameter has been added.
+
 
 Endpoints
 ---------
@@ -80,6 +90,7 @@ Endpoints
    :query string ordering: Manually set the ordering of results. Valid fields to be used are ``id`` and ``position``.
                            Default: ``position``
    :query integer subevent: Only return quotas of the sub-event with the given ID
+   :query string with_availability: Set to ``true`` to get availability information. Can lead to increased answer times.
    :param organizer: The ``slug`` field of the organizer to fetch
    :param event: The ``slug`` field of the event to fetch
    :statuscode 200: no error
@@ -120,6 +131,7 @@ Endpoints
    :param organizer: The ``slug`` field of the organizer to fetch
    :param event: The ``slug`` field of the event to fetch
    :param id: The ``id`` field of the quota to fetch
+   :query string with_availability: Set to ``true`` to get availability information. Can lead to increased answer times.
    :statuscode 200: no error
    :statuscode 401: Authentication failure
    :statuscode 403: The requested organizer/event does not exist **or** you have no permission to view this resource.

src/pretix/api/serializers/item.py

@@ -408,10 +408,19 @@ class QuestionSerializer(I18nAwareModelSerializer):
 
 
 class QuotaSerializer(I18nAwareModelSerializer):
+    available = serializers.BooleanField(read_only=True)
+    available_number = serializers.IntegerField(read_only=True)
 
     class Meta:
         model = Quota
-        fields = ('id', 'name', 'size', 'items', 'variations', 'subevent', 'closed', 'close_when_sold_out', 'release_after_exit')
+        fields = ('id', 'name', 'size', 'items', 'variations', 'subevent', 'closed', 'close_when_sold_out',
+                  'release_after_exit', 'available', 'available_number')
+
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+        if 'request' not in self.context or self.context['request'].GET.get('with_availability') != 'true':
+            del self.fields['available']
+            del self.fields['available_number']
 
     def validate(self, data):
         data = super().validate(data)

src/pretix/api/views/item.py

@@ -477,6 +477,23 @@ class QuotaViewSet(ConditionalListView, viewsets.ModelViewSet):
     def get_queryset(self):
         return self.request.event.quotas.all()
 
+    def list(self, request, *args, **kwargs):
+        queryset = self.filter_queryset(self.get_queryset())
+
+        page = self.paginate_queryset(queryset)
+
+        if self.request.GET.get('with_availability') == 'true':
+            if page:
+                qa = QuotaAvailability()
+                qa.queue(*page)
+                qa.compute(allow_cache=False)
+                for q in page:
+                    q.available = qa.results[q][0] == Quota.AVAILABILITY_OK
+                    q.available_number = qa.results[q][1]
+
+        serializer = self.get_serializer(page, many=True)
+        return self.get_paginated_response(serializer.data)
+
     def perform_create(self, serializer):
         serializer.save(event=self.request.event)
         serializer.instance.log_action(
@@ -496,6 +513,7 @@ class QuotaViewSet(ConditionalListView, viewsets.ModelViewSet):
     def get_serializer_context(self):
         ctx = super().get_serializer_context()
         ctx['event'] = self.request.event
+        ctx['request'] = self.request
         return ctx
 
     def perform_update(self, serializer):