fix: bypass access checks when populating course blocks cache

Author: asadali145

lms/djangoapps/course_blocks/api.py

@@ -108,4 +108,5 @@ def get_course_blocks(
         transformers,
         starting_block_usage_key,
         collected_block_structure,
+        user,
     )

openedx/core/djangoapps/content/block_structure/manager.py

@@ -35,7 +35,7 @@ def __init__(self, root_block_usage_key, modulestore, cache):
         self.modulestore = modulestore
         self.store = BlockStructureStore(cache)
 
-    def get_transformed(self, transformers, starting_block_usage_key=None, collected_block_structure=None):
+    def get_transformed(self, transformers, starting_block_usage_key=None, collected_block_structure=None, user=None):
         """
         Returns the transformed Block Structure for the root_block_usage_key,
         starting at starting_block_usage_key, getting block data from the cache
@@ -57,11 +57,14 @@ def get_transformed(self, transformers, starting_block_usage_key=None, collected
                 get_collected.  Can be optionally provided if already available,
                 for optimization.
 
+            user (django.contrib.auth.models.User) - User object for
+                which the block structure is to be transformed.
+
         Returns:
             BlockStructureBlockData - A transformed block structure,
                 starting at starting_block_usage_key.
         """
-        block_structure = collected_block_structure.copy() if collected_block_structure else self.get_collected()
+        block_structure = collected_block_structure.copy() if collected_block_structure else self.get_collected(user)
 
         if starting_block_usage_key:
             # Override the root_block_usage_key so traversals start at the
@@ -77,7 +80,7 @@ def get_transformed(self, transformers, starting_block_usage_key=None, collected
         transformers.transform(block_structure)
         return block_structure
 
-    def get_collected(self):
+    def get_collected(self, user=None):
         """
         Returns the collected Block Structure for the root_block_usage_key,
         getting block data from the cache and modulestore, as needed.
@@ -86,6 +89,10 @@ def get_collected(self):
         the modulestore is accessed if needed (at cache miss), and the
         transformers data is collected if needed.
 
+        In the case of a cache miss, the function bypasses runtime access checks for the current
+        user. This is done to prevent inconsistencies in the data, which can occur when
+        certain blocks are inaccessible due to access restrictions.
+
         Returns:
             BlockStructureBlockData - A collected block structure,
                 starting at root_block_usage_key, with collected data
@@ -99,7 +106,15 @@ def get_collected(self):
             BlockStructureTransformers.verify_versions(block_structure)
 
         except (BlockStructureNotFound, TransformerDataIncompatible):
-            block_structure = self._update_collected()
+            if user:
+                # This bypasses the runtime access checks. When we are populating the course blocks cache,
+                # we do not want to perform access checks. Access checks result in inconsistent blocks where
+                # inaccessible blocks are missing from the cache. Cached course blocks are then used for all the users.
+                user.known = False
+                block_structure = self._update_collected()
+                user.known = True
+            else:
+                block_structure = self._update_collected()
 
         return block_structure