feat: add API to return list of downstream blocks for an upstream

cms/djangoapps/contentstore/models.py

@@ -202,6 +202,15 @@ def get_by_downstream_context(cls, downstream_context_key: CourseKey) -> QuerySe
             "upstream_block__learning_package"
         )
 
+    @classmethod
+    def get_by_upstream_usage_key(cls, upstream_usage_key: UsageKey) -> QuerySet["PublishableEntityLink"]:
+        """
+        Get all downstream context keys for given upstream usage key
+        """
+        return cls.objects.filter(
+            upstream_usage_key=upstream_usage_key,
+        )
+
 
 class LearningContextLinksStatusChoices(models.TextChoices):
     """

cms/djangoapps/contentstore/rest_api/v2/urls.py

@@ -29,6 +29,11 @@
         downstreams.UpstreamListView.as_view(),
         name='upstream-list'
     ),
+    re_path(
+        f'^upstream/{settings.USAGE_KEY_PATTERN}/downstream-links$',
+        downstreams.DownstreamContextListView.as_view(),
+        name='downstream-link-list'
+    ),
     re_path(
         fr'^downstreams/{settings.USAGE_KEY_PATTERN}/sync$',
         downstreams.SyncFromUpstreamView.as_view(),

cms/djangoapps/contentstore/rest_api/v2/views/downstreams.py

@@ -40,6 +40,11 @@
       400: Downstream block is not linked to upstream content.
       404: Downstream block not found or user lacks permission to edit it.
 
+  /api/contentstore/v2/upstream/{usage_key_string}/downstream-links
+
+    GET: List all downstream blocks linked to a library block.
+        200: A list of downstream usage_keys linked to the library block.
+
   # NOT YET IMPLEMENTED -- Will be needed for full Libraries Relaunch in ~Teak.
   /api/contentstore/v2/downstreams
   /api/contentstore/v2/downstreams?course_id=course-v1:A+B+C&ready_to_sync=true
@@ -137,6 +142,31 @@ def get(self, request: _AuthenticatedRequest, course_key_string: str):
         return Response(serializer.data)
 
 
+@view_auth_classes()
+class DownstreamContextListView(DeveloperErrorViewMixin, APIView):
+    """
+    Serves library block->downstream usage keys
+    """
+    def get(self, request: _AuthenticatedRequest, usage_key_string: str) -> Response:
+        """
+        Fetches downstream links for given publishable entity
+        """
+        try:
+            usage_key = UsageKey.from_string(usage_key_string)
+        except InvalidKeyError as exc:
+            raise ValidationError(detail=f"Malformed usage key: {usage_key_string}") from exc
+
+        downstream_usage_key_list = (
+            PublishableEntityLink
+            .get_by_upstream_usage_key(upstream_usage_key=usage_key)
+            .values_list("downstream_usage_key", flat=True)
+        )
+
+        downstream_usage_key_str_list = [str(usage_key) for usage_key in downstream_usage_key_list]
+
+        return Response(downstream_usage_key_str_list)
+
+
 @view_auth_classes(is_authenticated=True)
 class DownstreamView(DeveloperErrorViewMixin, APIView):
     """

cms/djangoapps/contentstore/rest_api/v2/views/tests/test_downstreams.py

@@ -66,6 +66,20 @@ def setUp(self):
         self.downstream_html_key = BlockFactory.create(
             category='html', parent=unit, upstream=MOCK_HTML_UPSTREAM_REF, upstream_version=1,
         ).usage_key
+
+        self.another_course = CourseFactory.create(display_name="Another Course")
+        another_chapter = BlockFactory.create(category="chapter", parent=self.another_course)
+        another_sequential = BlockFactory.create(category="sequential", parent=another_chapter)
+        another_unit = BlockFactory.create(category="vertical", parent=another_sequential)
+        self.another_video_keys = []
+        for _ in range(3):
+            # Adds 3 videos linked to the same upstream
+            self.another_video_keys.append(
+                BlockFactory.create(
+                    category="video", parent=another_unit, upstream=MOCK_UPSTREAM_REF, upstream_version=123,
+                ).usage_key
+            )
+
         self.fake_video_key = self.course.id.make_usage_key("video", "NoSuchVideo")
         self.superuser = UserFactory(username="superuser", password="password", is_staff=True, is_superuser=True)
         self.learner = UserFactory(username="learner", password="password")
@@ -339,3 +353,23 @@ def test_200_all_upstreams(self):
             },
         ]
         self.assertListEqual(data, expected)
+
+
+class GetDownstreamContextsTest(_BaseDownstreamViewTestMixin, SharedModuleStoreTestCase):
+    """
+    Test that `GET /api/v2/contentstore/upstream/:usage_key/downstream-links returns list of
+    linked blocks usage_keys in given upstream entity (i.e. library block).
+    """
+    def call_api(self, usage_key_string):
+        return self.client.get(f"/api/contentstore/v2/upstream/{usage_key_string}/downstream-links")
+
+    def test_200_downstream_context_list(self):
+        """
+        Returns all downstream courses for given library block
+        """
+        self.client.login(username="superuser", password="password")
+        response = self.call_api(MOCK_UPSTREAM_REF)
+        assert response.status_code == 200
+        data = response.json()
+        expected = [str(self.downstream_video_key)] + [str(key) for key in self.another_video_keys]
+        self.assertListEqual(data, expected)

cms/djangoapps/contentstore/utils.py

@@ -2371,7 +2371,7 @@ def get_xblock_render_context(request, block):
     return ""
 
 
-def create_or_update_xblock_upstream_link(xblock, course_key: str | CourseKey, created: datetime | None = None):
+def create_or_update_xblock_upstream_link(xblock, course_key: str | CourseKey, created: datetime | None = None) -> None:
     """
     Create or update upstream->downstream link in database for given xblock.
     """

openedx/core/djangoapps/content/search/documents.py

@@ -47,9 +47,9 @@ class Fields:
     context_key = "context_key"
     org = "org"
     access_id = "access_id"  # .models.SearchAccess.id
-    # breadcrumbs: an array of {"display_name": "..."} entries. First one is the name of the course/library itself.
+    # breadcrumbs: an array of {"display_name": "...", "usage_key": "...", "url": "..."} entries.
+    # First one is the name of the course/library itself.
     # After that is the name of any parent Section/Subsection/Unit/etc.
-    # It's a list of dictionaries because for now we just include the name of each but in future we may add their IDs.
     breadcrumbs = "breadcrumbs"
     # tags (dictionary)
     # See https://blog.meilisearch.com/nested-hierarchical-facets-guide/
@@ -199,6 +199,7 @@ def _fields_from_block(block) -> dict:
     class implementation returns only:
         {"content": {"display_name": "..."}, "content_type": "..."}
     """
+
     block_type = block.scope_ids.block_type
     block_data = {
         Fields.usage_key: str(block.usage_key),
@@ -213,6 +214,9 @@ class implementation returns only:
     }
     # Get the breadcrumbs (course, section, subsection, etc.):
     if block.usage_key.context_key.is_course:  # Getting parent is not yet implemented in Learning Core (for libraries).
+        # Import here to avoid circular imports
+        from cms.djangoapps.contentstore.utils import reverse_course_url, reverse_usage_url
+
         cur_block = block
         while cur_block.parent:
             if not cur_block.has_cached_parent:
@@ -225,6 +229,18 @@ class implementation returns only:
             }
             if cur_block.scope_ids.block_type != "course":
                 parent_data["usage_key"] = str(cur_block.usage_key)
+                # Section and subsections don't have URLs in the CMS
+                if cur_block.scope_ids.block_type not in ["chapter", "sequential"]:
+                    parent_data["url"] = (
+                        reverse_course_url("course_handler", cur_block.context_key) +
+                        reverse_usage_url("container_handler", cur_block.usage_key)
+                    )
+            else:
+                parent_data["url"] = (
+                    reverse_course_url("course_handler", cur_block.context_key) +
+                    reverse_usage_url("container_handler", cur_block.usage_key)
+                )
+
             block_data[Fields.breadcrumbs].insert(
                 0,
                 parent_data,

openedx/core/djangoapps/content/search/tests/test_documents.py

@@ -158,6 +158,7 @@ def test_problem_block(self):
             "breadcrumbs": [
                 {
                     'display_name': 'Toy Course',
+                    'url': '/course/course-v1:edX+toy+2012_Fall/container/block-v1:edX+toy+2012_Fall+type@course+block@course',
                 },
                 {
                     'display_name': 'chapter',
@@ -170,6 +171,7 @@ def test_problem_block(self):
                 {
                     'display_name': 'vertical',
                     'usage_key': 'block-v1:edX+toy+2012_Fall+type@vertical+block@vertical_test',
+                    'url': '/course/course-v1:edX+toy+2012_Fall/container/block-v1:edX+toy+2012_Fall+type@vertical+block@vertical_test',
                 },
             ],
             "content": {
@@ -208,6 +210,7 @@ def test_html_block(self):
             "breadcrumbs": [
                 {
                     'display_name': 'Toy Course',
+                    'url': '/course/course-v1:edX+toy+2012_Fall/container/block-v1:edX+toy+2012_Fall+type@course+block@course',
                 },
                 {
                     'display_name': 'Overview',
@@ -251,6 +254,7 @@ def test_video_block_untagged(self):
             "breadcrumbs": [
                 {
                     'display_name': 'Toy Course',
+                    'url': '/course/course-v1:edX+toy+2012_Fall/container/block-v1:edX+toy+2012_Fall+type@course+block@course',
                 },
                 {
                     'display_name': 'Overview',