feat: add coerce_to_parent_course query param to basic content-metada…

…ta endpoint

ENT-9840

enterprise_catalog/apps/api/v1/views/content_metadata.py

@@ -1,5 +1,7 @@
 import uuid
 
+from django.db.models import Q
+from django.shortcuts import get_object_or_404
 from edx_rest_framework_extensions.auth.jwt.authentication import (
     JwtAuthentication,
 )
@@ -12,6 +14,7 @@
     PageNumberWithSizePagination,
 )
 from enterprise_catalog.apps.api.v1.serializers import ContentMetadataSerializer
+from enterprise_catalog.apps.catalog.constants import COURSE_RUN
 from enterprise_catalog.apps.catalog.models import ContentMetadata
 
 
@@ -47,16 +50,80 @@ class ContentMetadataView(viewsets.ReadOnlyModelViewSet):
     queryset = ContentMetadata.objects.all()
     pagination_class = PageNumberWithSizePagination
 
+    @property
+    def pk_is_object_id(self):
+        return self.kwargs.get('pk', '').isdigit()
+
+    @property
+    def pk_is_content_uuid(self):
+        return not self.pk_is_object_id and is_valid_uuid(self.kwargs.get('pk'))
+
+    @property
+    def pk_is_content_key(self):
+        return not self.pk_is_object_id and not self.pk_is_content_uuid
+
+    @property
+    def coerce_to_parent_course(self):
+        return self.request.query_params.get('coerce_to_parent_course', False)
+
     def get_queryset(self, **kwargs):
         """
         Returns all content metadata objects filtered by an optional request query param (LIST) ``content_identifiers``
+
+        If ``?coerce_to_parent_course=true` is passed to the list endpoint, any course runs which
+        would have been returned are coerced into their parent course in the response. No course
+        runs are returned when this setting is true.
         """
-        content_filters = self.request.query_params.getlist('content_identifiers')
         queryset = self.queryset
+
+        # Find all directly requested content
+        content_filters = self.request.query_params.getlist('content_identifiers')
+        queryset_direct = None
         if content_filters:
             content_uuids, content_keys = partition(is_valid_uuid, content_filters)
-            if content_keys:
-                queryset = queryset.filter(content_key__in=content_filters)
-            if content_uuids:
-                queryset = queryset.filter(content_uuid__in=content_filters)
+            queryset_direct = self.queryset.filter(
+                Q(content_uuid__in=content_uuids) | Q(content_key__in=content_keys)
+            )
+            queryset = queryset_direct
+
+        # If ``?parent_course=true`` was passed, exclude course runs.
+        if self.coerce_to_parent_course:
+            query_filters = ~Q(content_type=COURSE_RUN)
+            # If ``?content_identifiers=`` was passed, follow any matched course run objects back up
+            # to their parent courses and include those in the response.
+            if content_filters:
+                parent_content_keys = (
+                    record[0] for record in
+                    queryset_direct.filter(content_type=COURSE_RUN).values_list('parent_content_key')
+                )
+                all_content_keys_to_find = content_keys+parent_content_keys
+                query_filters &= (
+                    Q(content_uuid__in=content_uuids) | Q(content_key__in=all_content_keys_to_find)
+                )
+            queryset = self.queryset.filter(query_filters)
+
         return queryset
+
+    def retrieve(self, request, *args, pk=None, **kwargs):
+        """
+        Override to support querying by content key/uuid, and to optionally coerce runs to courses.
+        """
+        # Support alternative pk types besisdes just the raw object IDs (which are completely opaque
+        # to API clients).
+        obj = None
+        if self.pk_is_content_uuid:
+            obj = get_object_or_404(self.queryset, content_uuid=pk)
+        if self.pk_is_content_key:
+            obj = get_object_or_404(self.queryset, content_key=pk)
+        else:
+            obj = get_object_or_404(self.queryset, pk=pk)
+
+        # Coerce course runs to courses if requested.
+        if self.coerce_to_parent_course:
+            if obj.content_type == COURSE_RUN:
+                obj = get_object_or_404(self.queryset, content_key=obj.parent_content_key)
+
+        # Finally, call super's retrieve() which has more DRF guts that are best not duplicated in
+        # this codebase.
+        pk_to_retrieve = obj.id if obj else pk
+        return super().retrieve(request, *args, pk=pk_to_retrieve, **kwargs)