fix: [FC-0092] Fix 500 on return_type is list

lms/djangoapps/course_api/blocks/tests/test_views.py

@@ -516,7 +516,7 @@ def test_filter_discussion_xblocks(self, is_openedx_provider, return_type):
         def blocks_has_discussion_xblock(blocks):
             if isinstance(blocks, ReturnList):
                 for value in blocks:
-                    if value.get('type') == 'discussion':
+                    if value['type'] == 'discussion':
                         return True
             else:
                 for key, value in blocks.items():

lms/djangoapps/course_api/blocks/utils.py

@@ -28,11 +28,11 @@ def filter_discussion_xblocks_from_response(response, course_key):
             ]
         # Filtering discussion xblocks keys from blocks
         if isinstance(response.data, ReturnList):
-            filtered_blocks = {
-                value.get('id'): value
+            filtered_blocks = [
+                value
                 for value in response.data
                 if value.get('type') != 'discussion'
-            }
+            ]
         else:
             filtered_blocks = {
                 key: value
@@ -41,17 +41,29 @@ def filter_discussion_xblocks_from_response(response, course_key):
             }
         # Removing reference of discussion xblocks from unit
         # These references needs to be removed because they no longer exist
-        for _, block_data in filtered_blocks.items():
-            for key in ['descendants', 'children']:
-                descendants = block_data.get(key, [])
-                if descendants:
-                    descendants = [
-                        descendant for descendant in descendants
-                        if descendant not in discussion_xblocks
-                    ]
-                    block_data[key] = descendants
         if isinstance(response.data, ReturnList):
-            response.data = filtered_blocks
+            for block_data in filtered_blocks:
+                _put_xblock_descendants(block_data, discussion_xblocks)
+        else:
+            for _, block_data in filtered_blocks.items():
+                _put_xblock_descendants(block_data, discussion_xblocks)
+
+        if isinstance(response.data, ReturnList):
+            response.data = ReturnList(filtered_blocks, serializer=None)
         else:
             response.data['blocks'] = filtered_blocks
     return response
+
+
+def _put_xblock_descendants(block_data, discussion_xblocks):
+    """
+    Put descendants into xblock data if they existed before filtering.
+    """
+    for key in ['descendants', 'children']:
+        descendants = block_data.get(key, [])
+        if descendants:
+            descendants = [
+                descendant for descendant in descendants
+                if descendant not in discussion_xblocks
+            ]
+            block_data[key] = descendants

lms/djangoapps/course_api/blocks/views.py

@@ -330,12 +330,14 @@ def list(self, request, hide_access_denials=False):  # pylint: disable=arguments
 
                 if course_block.get('type') == 'course':
                     root = course_block['id']
+                else:
+                    root = str(course_usage_key)
         else:
             root = response.data['root']
             course_blocks = response.data['blocks']
 
         if not root:
-            raise ValueError(f"Unable to find course block in {course_key_string}")
+            raise ValidationError(f"Unable to find course block in '{course_key_string}'")
 
         recurse_mark_complete(root, course_blocks)
         return response