API: Allow bulk-cration of cart positions

src/pretix/api/views/cart.py

@@ -21,14 +21,18 @@
 #
 from django.db import transaction
 from rest_framework import status, viewsets
+from rest_framework.decorators import action
+from rest_framework.exceptions import ValidationError
 from rest_framework.filters import OrderingFilter
 from rest_framework.mixins import CreateModelMixin, DestroyModelMixin
 from rest_framework.response import Response
+from rest_framework.settings import api_settings
 
 from pretix.api.serializers.cart import (
     CartPositionCreateSerializer, CartPositionSerializer,
 )
 from pretix.base.models import CartPosition
+from pretix.base.services.locking import NoLockManager
 
 
 class CartPositionViewSet(CreateModelMixin, DestroyModelMixin, viewsets.ReadOnlyModelViewSet):
@@ -50,18 +54,61 @@ class CartPositionViewSet(CreateModelMixin, DestroyModelMixin, viewsets.ReadOnly
     def get_serializer_context(self):
         ctx = super().get_serializer_context()
         ctx['event'] = self.request.event
+        ctx['quota_cache'] = {}
         return ctx
 
     def create(self, request, *args, **kwargs):
         serializer = CartPositionCreateSerializer(data=request.data, context=self.get_serializer_context())
         serializer.is_valid(raise_exception=True)
-        with transaction.atomic():
+        with transaction.atomic(), self.request.event.lock():
             self.perform_create(serializer)
-            cp = serializer.instance
-            serializer = CartPositionSerializer(cp, context=serializer.context)
-
+        cp = serializer.instance
+        serializer = CartPositionSerializer(cp, context=serializer.context)
         headers = self.get_success_headers(serializer.data)
         return Response(serializer.data, status=status.HTTP_201_CREATED, headers=headers)
 
+    @action(detail=False, methods=['POST'])
+    def bulk_create(self, request, *args, **kwargs):
+        if not isinstance(request.data, list):  # noqa
+            return Response({"error": "Please supply a list"}, status=status.HTTP_400_BAD_REQUEST)
+
+        ctx = self.get_serializer_context()
+        with transaction.atomic():
+            serializers = [
+                CartPositionCreateSerializer(data=d, context=ctx)
+                for d in request.data
+            ]
+
+            lockfn = self.request.event.lock
+            if not any(s.is_valid(raise_exception=False) for s in serializers):
+                lockfn = NoLockManager
+
+            results = []
+            with lockfn():
+                for s in serializers:
+                    if s.is_valid(raise_exception=False):
+                        try:
+                            cp = s.save()
+                        except ValidationError as e:
+                            results.append({
+                                'success': False,
+                                'data': None,
+                                'errors': {api_settings.NON_FIELD_ERRORS_KEY: e.detail},
+                            })
+                        else:
+                            results.append({
+                                'success': True,
+                                'data': CartPositionSerializer(cp, context=ctx).data,
+                                'errors': None,
+                            })
+                    else:
+                        results.append({
+                            'success': False,
+                            'data': None,
+                            'errors': s.errors,
+                        })
+
+        return Response({'results': results}, status=status.HTTP_200_OK)
+
     def perform_create(self, serializer):
         serializer.save()