Fix sequence navigation issues for CCX courses

MA-2258

common/lib/xmodule/xmodule/modulestore/__init__.py

@@ -38,6 +38,11 @@ new_contract('XBlock', XBlock)
 LIBRARY_ROOT = 'library.xml'
 COURSE_ROOT = 'course.xml'
 
+# List of names of computed fields on xmodules that are of type usage keys.
+# This list can be used to determine which fields need to be stripped of
+# extraneous usage key data when entering/exiting modulestores.
+XMODULE_FIELDS_WITH_USAGE_KEYS = ['location', 'parent']
+
 
 class ModuleStoreEnum(object):
     """

common/lib/xmodule/xmodule/modulestore/mixed.py

@@ -17,8 +17,7 @@ from opaque_keys.edx.locator import LibraryLocator
 from opaque_keys.edx.locations import SlashSeparatedCourseKey
 from xmodule.assetstore import AssetMetadata
 
-from . import ModuleStoreWriteBase
-from . import ModuleStoreEnum
+from . import ModuleStoreWriteBase, ModuleStoreEnum, XMODULE_FIELDS_WITH_USAGE_KEYS
 from .exceptions import ItemNotFoundError, DuplicateCourseError
 from .draft_and_published import ModuleStoreDraftAndPublished
 from .split_migrator import SplitMigrator
@@ -67,8 +66,9 @@ def strip_key(func):
                 retval = retval.version_agnostic()
             if rem_branch and hasattr(retval, 'for_branch'):
                 retval = retval.for_branch(None)
-            if hasattr(retval, 'location'):
-                retval.location = strip_key_func(retval.location)
+            for field_name in XMODULE_FIELDS_WITH_USAGE_KEYS:
+                if hasattr(retval, field_name):
+                    setattr(retval, field_name, strip_key_func(getattr(retval, field_name)))
             return retval
 
         # function for stripping both, collection of, and individual, values

common/lib/xmodule/xmodule/modulestore/mongo/base.py

@@ -127,6 +127,8 @@ class MongoKeyValueStore(InheritanceKeyValueStore):
     def set(self, key, value):
         if key.scope == Scope.children:
             self._children = value
+        elif key.scope == Scope.parent:
+            self._parent = value
         elif key.scope == Scope.settings:
             self._metadata[key.field_name] = value
         elif key.scope == Scope.content:

common/lib/xmodule/xmodule/modulestore/tests/test_mongo.py

@@ -767,15 +767,15 @@ class TestMongoKeyValueStore(unittest.TestCase):
     def test_write(self):
         yield (self._check_write, KeyValueStore.Key(Scope.content, None, None, 'foo'), 'new_data')
         yield (self._check_write, KeyValueStore.Key(Scope.children, None, None, 'children'), [])
+        yield (self._check_write, KeyValueStore.Key(Scope.children, None, None, 'parent'), None)
         yield (self._check_write, KeyValueStore.Key(Scope.settings, None, None, 'meta'), 'new_settings')
-        # write Scope.parent raises InvalidScope, which is covered in test_write_invalid_scope
 
     def test_write_non_dict_data(self):
         self.kvs = MongoKeyValueStore('xml_data', self.parent, self.children, self.metadata)
         self._check_write(KeyValueStore.Key(Scope.content, None, None, 'data'), 'new_data')
 
     def test_write_invalid_scope(self):
-        for scope in (Scope.preferences, Scope.user_info, Scope.user_state, Scope.parent):
+        for scope in (Scope.preferences, Scope.user_info, Scope.user_state):
             with assert_raises(InvalidScopeError):
                 self.kvs.set(KeyValueStore.Key(scope, None, None, 'foo'), 'new_value')