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Below I'm cataloging each and every read/write access to the courseware StudentModule (CSM) Django model. It's essential to know of each access due to our pending work to encapsulate all CSM access behind an interface. The interface backend will support both the present Django ORM and a Cassandra backend to better handle student traffic at scale. Dave Ormsbee has authored this page to capture existing CSM query patterns - the catalog below looks at all code in edx-platform and catalogs access in each file therein.

lms/djangoapps/courseware/model_data.py

Reads

Call Chain

Query

Maps To Query

FieldDataCache.__init__() / FieldDataCache.add_descriptor_descendants()
FieldDataCache.add_descriptors_to_cache()
FieldDataCache._retrieve_fields()

return self._chunked_query(
 StudentModule,
 'module_state_key__in',
 self._all_usage_ids(descriptors),
 course_id=self.course_id,
 student=self.user.pk,
)
Ultimately, a objects.filter() call.
 

Writes

Call Chain

Query

Maps To Query
FieldDataCache.find_or_create()
DjangoKeyValueStore.set_many()

field_object = StudentModule(
course_id=self.course_id,
student_id=key.user_id,
module_state_key=key.block_scope_id,
state=json.dumps({}),
module_type=key.block_scope_id.block_type,
)

 
DjangoKeyValueStore.set_many()StudentModule.save() 

DjangoKeyValueStore.delete()

StudentModule.save()