Add implementation of get_many and set_many to DjangoXBlockUserStateClient

lms/djangoapps/courseware/user_state_client.py

@@ -3,10 +3,20 @@ An implementation of :class:`XBlockUserStateClient`, which stores XBlock Scope.u
 data in a Django ORM model.
 """
 
-from xblock_user_state.interface import DjangoXBlockUserStateClient
+import itertools
+from operator import attrgetter
+
+try:
+    import simplejson as json
+except ImportError:
+    import json
+
+from xblock.fields import Scope
+from xblock_user_state.interface import XBlockUserStateClient
+from courseware.models import StudentModule
 
 
-class DjangoXBlockUserStateClient(DjangoXBlockUserStateClient):
+class DjangoXBlockUserStateClient(XBlockUserStateClient):
     """
     An interface that uses the Django ORM StudentModule as a backend.
     """
@@ -29,7 +39,11 @@ class DjangoXBlockUserStateClient(DjangoXBlockUserStateClient):
         """
         pass
 
-    def get(username, block_key, scope=Scope.user_state, fields=None):
+    def __init__(self, user):
+        self._student_module_cache = {}
+        self.user = user
+
+    def get(self, username, block_key, scope=Scope.user_state, fields=None):
         """
         Retrieve the stored XBlock state for a single xblock usage.
 
@@ -45,6 +59,7 @@ class DjangoXBlockUserStateClient(DjangoXBlockUserStateClient):
         Raises:
             DoesNotExist if no entry is found.
         """
+        assert self.user.username == username
         try:
             _usage_key, state = next(self.get_many(username, [block_key], scope, fields=fields))
         except StopIteration:
@@ -52,19 +67,68 @@ class DjangoXBlockUserStateClient(DjangoXBlockUserStateClient):
 
         return state
 
-    def set(username, block_key, state, scope=Scope.user_state):
+    def set(self, username, block_key, state, scope=Scope.user_state):
         """
         Set fields for a particular XBlock.
 
         Arguments:
             username: The name of the user whose state should be retrieved
-            block_key (UsageKey): The UsageKey identifying which xblock state to load.
+            block_key (UsageKey): The UsageKey identifying which xblock state to update.
             state (dict): A dictionary mapping field names to values
             scope (Scope): The scope to load data from
         """
+        assert self.user.username == username
         self.set_many(username, {block_key: state}, scope)
 
-    def get_many(username, block_keys, scope=Scope.user_state, fields=None):
+    def delete(self, username, block_key, scope=Scope.user_state, fields=None):
+        """
+        Delete the stored XBlock state for a single xblock usage.
+
+        Arguments:
+            username: The name of the user whose state should be deleted
+            block_key (UsageKey): The UsageKey identifying which xblock state to delete.
+            scope (Scope): The scope to delete data from
+            fields: A list of fields to delete. If None, delete all stored fields.
+        """
+        assert self.user.username == username
+        return self.delete_many(username, [block_key], scope, fields=fields)
+
+    def _get_field_objects(self, username, block_keys):
+        """
+        Retrieve the :class:`~StudentModule`s for the supplied ``username`` and ``block_keys``.
+
+        Arguments:
+            username (str): The name of the user to load `StudentModule`s for.
+            block_keys (list of :class:`~UsageKey`): The set of XBlocks to load data for.
+        """
+        course_key_func = attrgetter('course_key')
+        by_course = itertools.groupby(
+            sorted(block_keys, key=course_key_func),
+            course_key_func,
+        )
+
+        for course_key, usage_keys in by_course:
+            not_cached = []
+            for usage_key in usage_keys:
+                if usage_key in self._student_module_cache:
+                    yield self._student_module_cache[usage_key]
+                else:
+                    not_cached.append(usage_key)
+
+            query = StudentModule.objects.chunked_filter(
+                'module_state_key__in',
+                not_cached,
+                student__username=username,
+                course_id=course_key,
+            )
+
+            for student_module in query:
+                usage_key = student_module.module_state_key.map_into_course(student_module.course_id)
+                self._student_module_cache[usage_key] = student_module
+                yield (student_module, usage_key)
+
+
+    def get_many(self, username, block_keys, scope=Scope.user_state, fields=None):
         """
         Retrieve the stored XBlock state for a single xblock usage.
 
@@ -78,11 +142,19 @@ class DjangoXBlockUserStateClient(DjangoXBlockUserStateClient):
             (UsageKey, field_state) tuples for each specified UsageKey in block_keys.
             field_state is a dict mapping field names to values.
         """
+        assert self.user.username == username
         if scope != Scope.user_state:
-            raise ValueError("Only Scope.user_state is supported")
-        raise NotImplementedError()
+            raise ValueError("Only Scope.user_state is supported, not {}".format(scope))
 
-    def set_many(username, block_keys_to_state, scope=Scope.user_state):
+        modules = self._get_field_objects(username, block_keys)
+        for module, usage_key in modules:
+            if module.state is None:
+                state = {}
+            else:
+                state = json.loads(module.state)
+            yield (usage_key, state)
+
+    def set_many(self, username, block_keys_to_state, scope=Scope.user_state):
         """
         Set fields for a particular XBlock.
 
@@ -94,17 +166,75 @@ class DjangoXBlockUserStateClient(DjangoXBlockUserStateClient):
                 :meth:`delete` or :meth:`delete_many`.
             scope (Scope): The scope to load data from
         """
+        assert self.user.username == username
         if scope != Scope.user_state:
             raise ValueError("Only Scope.user_state is supported")
-        raise NotImplementedError()
 
-    def get_history(username, block_key, scope=Scope.user_state):
+        field_objects = self._get_field_objects(username, block_keys_to_state.keys())
+        for field_object in field_objects:
+            usage_key = field_object.module_state_key.map_into_course(field_object.course_id)
+            current_state = json.loads(field_object.state)
+            current_state.update(block_keys_to_state.pop(usage_key))
+            field_object.state = json.dumps(current_state)
+            field_object.save()
+
+        for usage_key, state in block_keys_to_state.items():
+            student_module, created = StudentModule.objects.get_or_create(
+                student=self.user,
+                course_id=usage_key.course_key,
+                module_state_key=usage_key,
+                defaults={
+                    'state': json.dumps(state),
+                    'module_type': usage_key.block_type,
+                },
+            )
+
+            if not created:
+                if student_module.state is None:
+                    current_state = {}
+                else:
+                    current_state = json.loads(student_module.state)
+                current_state.update(state)
+                student_module.state = json.dumps(current_state)
+                # We just read this object, so we know that we can do an update
+                student_module.save(force_update=True)
+
+    def delete_many(self, username, block_keys, scope=Scope.user_state, fields=None):
+        """
+        Delete the stored XBlock state for a many xblock usages.
+
+        Arguments:
+            username: The name of the user whose state should be deleted
+            block_key (UsageKey): The UsageKey identifying which xblock state to delete.
+            scope (Scope): The scope to delete data from
+            fields: A list of fields to delete. If None, delete all stored fields.
+        """
+        assert self.user.username == username
+        if scope != Scope.user_state:
+            raise ValueError("Only Scope.user_state is supported")
+
+        student_modules = self._get_field_objects(username, block_keys)
+        for student_module, _ in student_modules:
+            if fields is None:
+                field_object.state = "{}"
+            else:
+                current_state = json.loads(field_object.state)
+                for field in fields:
+                    if field in current_state:
+                        del current_state[field]
+
+                student_module.state = json.dumps(current_state)
+            # We just read this object, so we know that we can do an update
+            student_module.save(force_update=True)
+
+    def get_history(self, username, block_key, scope=Scope.user_state):
         """We don't guarantee that history for many blocks will be fast."""
+        assert self.user.username == username
         if scope != Scope.user_state:
             raise ValueError("Only Scope.user_state is supported")
         raise NotImplementedError()
 
-    def iter_all_for_block(block_key, scope=Scope.user_state, batch_size=None):
+    def iter_all_for_block(self, block_key, scope=Scope.user_state, batch_size=None):
         """
         You get no ordering guarantees. Fetching will happen in batch_size
         increments. If you're using this method, you should be running in an
@@ -114,7 +244,7 @@ class DjangoXBlockUserStateClient(DjangoXBlockUserStateClient):
             raise ValueError("Only Scope.user_state is supported")
         raise NotImplementedError()
 
-    def iter_all_for_course(course_key, block_type=None, scope=Scope.user_state, batch_size=None):
+    def iter_all_for_course(self, course_key, block_type=None, scope=Scope.user_state, batch_size=None):
         """
         You get no ordering guarantees. Fetching will happen in batch_size
         increments. If you're using this method, you should be running in an