Merge pull request #624 from edx/dhm/flatten_kvs

xblock fields persist w/o breaking by scope

cms/djangoapps/contentstore/tests/test_crud.py

-'''
-Created on May 7, 2013
-
-@author: dmitchell
-'''
 import unittest
 from xmodule import templates
 from xmodule.modulestore.tests import persistent_factories
 from xmodule.course_module import CourseDescriptor
 from xmodule.modulestore.django import modulestore
 from xmodule.seq_module import SequenceDescriptor
-from xmodule.x_module import XModuleDescriptor
 from xmodule.capa_module import CapaDescriptor
 from xmodule.modulestore.locator import CourseLocator, BlockUsageLocator
 from xmodule.modulestore.exceptions import ItemNotFoundError
 from xmodule.html_module import HtmlDescriptor
+from xmodule.modulestore import inheritance
+from xmodule.x_module import XModuleDescriptor
 
 
 class TemplateTests(unittest.TestCase):
@@ -74,8 +70,8 @@ class TemplateTests(unittest.TestCase):
         test_course = persistent_factories.PersistentCourseFactory.create(org='testx', prettyid='tempcourse',
             display_name='fun test course', user_id='testbot')
 
-        test_chapter = XModuleDescriptor.load_from_json({'category': 'chapter',
-            'metadata': {'display_name': 'chapter n'}},
+        test_chapter = self.load_from_json({'category': 'chapter',
+            'fields': {'display_name': 'chapter n'}},
             test_course.system, parent_xblock=test_course)
         self.assertIsInstance(test_chapter, SequenceDescriptor)
         self.assertEqual(test_chapter.display_name, 'chapter n')
@@ -83,8 +79,8 @@ class TemplateTests(unittest.TestCase):
 
         # test w/ a definition (e.g., a problem)
         test_def_content = '<problem>boo</problem>'
-        test_problem = XModuleDescriptor.load_from_json({'category': 'problem',
-            'definition': {'data': test_def_content}},
+        test_problem = self.load_from_json({'category': 'problem',
+            'fields': {'data': test_def_content}},
             test_course.system, parent_xblock=test_chapter)
         self.assertIsInstance(test_problem, CapaDescriptor)
         self.assertEqual(test_problem.data, test_def_content)
@@ -98,12 +94,13 @@ class TemplateTests(unittest.TestCase):
         """
         test_course = persistent_factories.PersistentCourseFactory.create(org='testx', prettyid='tempcourse',
             display_name='fun test course', user_id='testbot')
-        test_chapter = XModuleDescriptor.load_from_json({'category': 'chapter',
-            'metadata': {'display_name': 'chapter n'}},
+        test_chapter = self.load_from_json({'category': 'chapter',
+            'fields': {'display_name': 'chapter n'}},
             test_course.system, parent_xblock=test_course)
         test_def_content = '<problem>boo</problem>'
-        test_problem = XModuleDescriptor.load_from_json({'category': 'problem',
-            'definition': {'data': test_def_content}},
+        # create child
+        _ = self.load_from_json({'category': 'problem',
+            'fields': {'data': test_def_content}},
             test_course.system, parent_xblock=test_chapter)
         # better to pass in persisted parent over the subdag so
         # subdag gets the parent pointer (otherwise 2 ops, persist dag, update parent children,
@@ -152,15 +149,24 @@ class TemplateTests(unittest.TestCase):
             parent_location=test_course.location, user_id='testbot')
         sub = persistent_factories.ItemFactory.create(display_name='subsection 1',
             parent_location=chapter.location, user_id='testbot', category='vertical')
-        first_problem = persistent_factories.ItemFactory.create(display_name='problem 1',
-            parent_location=sub.location, user_id='testbot', category='problem', data="<problem></problem>")
+        first_problem = persistent_factories.ItemFactory.create(
+            display_name='problem 1', parent_location=sub.location, user_id='testbot', category='problem',
+            data="<problem></problem>"
+        )
         first_problem.max_attempts = 3
+        first_problem.save()  # decache the above into the kvs
         updated_problem = modulestore('split').update_item(first_problem, 'testbot')
-        updated_loc = modulestore('split').delete_item(updated_problem.location, 'testbot')
+        self.assertIsNotNone(updated_problem.previous_version)
+        self.assertEqual(updated_problem.previous_version, first_problem.update_version)
+        self.assertNotEqual(updated_problem.update_version, first_problem.update_version)
+        updated_loc = modulestore('split').delete_item(updated_problem.location, 'testbot', delete_children=True)
 
-        second_problem = persistent_factories.ItemFactory.create(display_name='problem 2',
+        second_problem = persistent_factories.ItemFactory.create(
+            display_name='problem 2',
             parent_location=BlockUsageLocator(updated_loc, usage_id=sub.location.usage_id),
-            user_id='testbot', category='problem', data="<problem></problem>")
+            user_id='testbot', category='problem',
+            data="<problem></problem>"
+        )
 
         # course root only updated 2x
         version_history = modulestore('split').get_block_generations(test_course.location)
@@ -184,3 +190,48 @@ class TemplateTests(unittest.TestCase):
 
         version_history = modulestore('split').get_block_generations(second_problem.location)
         self.assertNotEqual(version_history.locator.version_guid, first_problem.location.version_guid)
+
+    # ================================= JSON PARSING ===========================
+    # These are example methods for creating xmodules in memory w/o persisting them.
+    # They were in x_module but since xblock is not planning to support them but will
+    # allow apps to use this type of thing, I put it here.
+    @staticmethod
+    def load_from_json(json_data, system, default_class=None, parent_xblock=None):
+        """
+        This method instantiates the correct subclass of XModuleDescriptor based
+        on the contents of json_data. It does not persist it and can create one which
+        has no usage id.
+
+        parent_xblock is used to compute inherited metadata as well as to append the new xblock.
+
+        json_data:
+        - 'location' : must have this field
+        - 'category': the xmodule category (required or location must be a Location)
+        - 'metadata': a dict of locally set metadata (not inherited)
+        - 'children': a list of children's usage_ids w/in this course
+        - 'definition':
+        - '_id' (optional): the usage_id of this. Will generate one if not given one.
+        """
+        class_ = XModuleDescriptor.load_class(
+            json_data.get('category', json_data.get('location', {}).get('category')),
+            default_class
+        )
+        usage_id = json_data.get('_id', None)
+        if not '_inherited_settings' in json_data and parent_xblock is not None:
+            json_data['_inherited_settings'] = parent_xblock.xblock_kvs.get_inherited_settings().copy()
+            json_fields = json_data.get('fields', {})
+            for field in inheritance.INHERITABLE_METADATA:
+                if field in json_fields:
+                    json_data['_inherited_settings'][field] = json_fields[field]
+
+        new_block = system.xblock_from_json(class_, usage_id, json_data)
+        if parent_xblock is not None:
+            children = parent_xblock.children
+            children.append(new_block)
+            # trigger setter method by using top level field access
+            parent_xblock.children = children
+            # decache pending children field settings (Note, truly persisting at this point would break b/c
+            # persistence assumes children is a list of ids not actual xblocks)
+            parent_xblock.save()
+        return new_block
+

cms/djangoapps/contentstore/views/item.py

@@ -58,14 +58,12 @@ def save_item(request):
         # 'apply' the submitted metadata, so we don't end up deleting system metadata
         existing_item = modulestore().get_item(item_location)
         for metadata_key in request.POST.get('nullout', []):
-            # [dhm] see comment on _get_xblock_field
             _get_xblock_field(existing_item, metadata_key).write_to(existing_item, None)
 
         # update existing metadata with submitted metadata (which can be partial)
         # IMPORTANT NOTE: if the client passed 'null' (None) for a piece of metadata that means 'remove it'. If
         # the intent is to make it None, use the nullout field
         for metadata_key, value in request.POST.get('metadata', {}).items():
-            # [dhm] see comment on _get_xblock_field
             field = _get_xblock_field(existing_item, metadata_key)
 
             if value is None:
@@ -82,32 +80,15 @@ def save_item(request):
     return JsonResponse()
 
 
-# [DHM] A hack until we implement a permanent soln. Proposed perm solution is to make namespace fields also top level
-# fields in xblocks rather than requiring dereference through namespace but we'll need to consider whether there are
-# plausible use cases for distinct fields w/ same name in different namespaces on the same blocks.
-# The idea is that consumers of the xblock, and particularly the web client, shouldn't know about our internal
-# representation (namespaces as means of decorating all modules).
-# Given top-level access, the calls can simply be setattr(existing_item, field, value) ...
-# Really, this method should be elsewhere (e.g., xblock). We also need methods for has_value (v is_default)...
 def _get_xblock_field(xblock, field_name):
     """
     A temporary function to get the xblock field either from the xblock or one of its namespaces by name.
     :param xblock:
     :param field_name:
     """
-    def find_field(fields):
-        for field in fields:
-            if field.name == field_name:
-                return field
-
-    found = find_field(xblock.fields)
-    if found:
-        return found
-    for namespace in xblock.namespaces:
-        found = find_field(getattr(xblock, namespace).fields)
-        if found:
-            return found
-
+    for field in xblock.iterfields():
+        if field.name == field_name:
+            return field
 
 @login_required
 @expect_json

common/lib/xmodule/xmodule/modulestore/split_mongo/caching_descriptor_system.py

@@ -11,18 +11,17 @@ from .split_mongo_kvs import SplitMongoKVS, SplitMongoKVSid
 
 log = logging.getLogger(__name__)
 
-# TODO should this be here or w/ x_module or ???
 class CachingDescriptorSystem(MakoDescriptorSystem):
     """
     A system that has a cache of a course version's json that it will use to load modules
     from, with a backup of calling to the underlying modulestore for more data.
 
-    Computes the metadata inheritance upon creation.
+    Computes the settings (nee 'metadata') inheritance upon creation.
     """
     def __init__(self, modulestore, course_entry, module_data, lazy,
         default_class, error_tracker, render_template):
         """
-        Computes the metadata inheritance and sets up the cache.
+        Computes the settings inheritance and sets up the cache.
 
         modulestore: the module store that can be used to retrieve additional
         modules
@@ -50,9 +49,10 @@ class CachingDescriptorSystem(MakoDescriptorSystem):
         self.default_class = default_class
         # TODO see if self.course_id is needed: is already in course_entry but could be > 1 value
         # Compute inheritance
-        modulestore.inherit_metadata(course_entry.get('blocks', {}),
-            course_entry.get('blocks', {})
-            .get(course_entry.get('root')))
+        modulestore.inherit_settings(
+            course_entry.get('blocks', {}),
+            course_entry.get('blocks', {}).get(course_entry.get('root'))
+        )
 
     def _load_item(self, usage_id, course_entry_override=None):
         # TODO ensure all callers of system.load_item pass just the id
@@ -73,9 +73,8 @@ class CachingDescriptorSystem(MakoDescriptorSystem):
     def xblock_from_json(self, class_, usage_id, json_data, course_entry_override=None):
         if course_entry_override is None:
             course_entry_override = self.course_entry
-        # most likely a lazy loader but not the id directly
+        # most likely a lazy loader or the id directly
         definition = json_data.get('definition', {})
-        metadata = json_data.get('metadata', {})
 
         block_locator = BlockUsageLocator(
             version_guid=course_entry_override['_id'],
@@ -86,9 +85,8 @@ class CachingDescriptorSystem(MakoDescriptorSystem):
 
         kvs = SplitMongoKVS(
             definition,
-            json_data.get('children', []),
-            metadata,
-            json_data.get('_inherited_metadata'),
+            json_data.get('fields', {}),
+            json_data.get('_inherited_settings'),
             block_locator,
             json_data.get('category'))
         model_data = DbModel(kvs, class_, None,
@@ -111,10 +109,11 @@ class CachingDescriptorSystem(MakoDescriptorSystem):
                 error_msg=exc_info_to_str(sys.exc_info())
             )
 
-        module.edited_by = json_data.get('edited_by')
-        module.edited_on = json_data.get('edited_on')
-        module.previous_version = json_data.get('previous_version')
-        module.update_version = json_data.get('update_version')
+        edit_info = json_data.get('edit_info', {})
+        module.edited_by = edit_info.get('edited_by')
+        module.edited_on = edit_info.get('edited_on')
+        module.previous_version = edit_info.get('previous_version')
+        module.update_version = edit_info.get('update_version')
         module.definition_locator = self.modulestore.definition_locator(definition)
         # decache any pending field settings
         module.save()

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

@@ -11,44 +11,24 @@ class PersistentCourseFactory(factory.Factory):
     """
     Create a new course (not a new version of a course, but a whole new index entry).
 
-    keywords:
+    keywords: any xblock field plus (note, the below are filtered out; so, if they
+    become legitimate xblock fields, they won't be settable via this factory)
     * org: defaults to textX
     * prettyid: defaults to 999
-    * display_name
-    * user_id
-    * data (optional) the data payload to save in the course item
-    * metadata (optional) the metadata payload. If display_name is in the metadata, that takes
-    precedence over any display_name provided directly.
+    * master_branch: (optional) defaults to 'draft'
+    * user_id: (optional) defaults to 'test_user'
+    * display_name (xblock field): will default to 'Robot Super Course' unless provided
     """
     FACTORY_FOR = CourseDescriptor
 
-    org = 'testX'
-    prettyid = '999'
-    display_name = 'Robot Super Course'
-    user_id = "test_user"
-    data = None
-    metadata = None
-    master_version = 'draft'
-
     # pylint: disable=W0613
     @classmethod
-    def _create(cls, target_class, *args, **kwargs):
-
-        org = kwargs.get('org')
-        prettyid = kwargs.get('prettyid')
-        display_name = kwargs.get('display_name')
-        user_id = kwargs.get('user_id')
-        data = kwargs.get('data')
-        metadata = kwargs.get('metadata', {})
-        if metadata is None:
-            metadata = {}
-        if 'display_name' not in metadata:
-            metadata['display_name'] = display_name
+    def _create(cls, target_class, org='testX', prettyid='999', user_id='test_user', master_branch='draft', **kwargs):
 
         # Write the data to the mongo datastore
         new_course = modulestore('split').create_course(
-            org, prettyid, user_id, metadata=metadata, course_data=data, id_root=prettyid,
-            master_version=kwargs.get('master_version'))
+            org, prettyid, user_id, fields=kwargs, id_root=prettyid,
+            master_branch=master_branch)
 
         return new_course
 
@@ -60,36 +40,24 @@ class PersistentCourseFactory(factory.Factory):
 class ItemFactory(factory.Factory):
     FACTORY_FOR = XModuleDescriptor
 
-    category = 'chapter'
-    user_id = 'test_user'
     display_name = factory.LazyAttributeSequence(lambda o, n: "{} {}".format(o.category, n))
 
     # pylint: disable=W0613
     @classmethod
-    def _create(cls, target_class, *args, **kwargs):
+    def _create(cls, target_class, parent_location, category='chapter',
+        user_id='test_user', definition_locator=None, **kwargs):
         """
-        Uses *kwargs*:
-
-        *parent_location* (required): the location of the course & possibly parent
+        passes *kwargs* as the new item's field values:
 
-        *category* (defaults to 'chapter')
+        :param parent_location: (required) the location of the course & possibly parent
 
-        *data* (optional): the data for the item
+        :param category: (defaults to 'chapter')
 
-        definition_locator (optional): the DescriptorLocator for the definition this uses or branches
-
-        *display_name* (optional): the display name of the item
-
-        *metadata* (optional): dictionary of metadata attributes (display_name here takes
-        precedence over the above attr)
+        :param definition_locator (optional): the DescriptorLocator for the definition this uses or branches
         """
-        metadata = kwargs.get('metadata', {})
-        if 'display_name' not in metadata and 'display_name' in kwargs:
-            metadata['display_name'] = kwargs['display_name']
-
-        return modulestore('split').create_item(kwargs['parent_location'], kwargs['category'],
-            kwargs['user_id'], definition_locator=kwargs.get('definition_locator'),
-            new_def_data=kwargs.get('data'), metadata=metadata)
+        return modulestore('split').create_item(
+            parent_location, category, user_id, definition_locator, fields=kwargs
+        )
 
     @classmethod
     def _build(cls, target_class, *args, **kwargs):

common/lib/xmodule/xmodule/x_module.py

@@ -7,7 +7,7 @@ from lxml import etree
 from collections import namedtuple
 from pkg_resources import resource_listdir, resource_string, resource_isdir
 
-from xmodule.modulestore import inheritance, Location
+from xmodule.modulestore import Location
 from xmodule.modulestore.exceptions import ItemNotFoundError, InsufficientSpecificationError, InvalidLocationError
 
 from xblock.core import XBlock, Scope, String, Integer, Float, List, ModelType
@@ -557,75 +557,6 @@ class XModuleDescriptor(XModuleFields, HTMLSnippet, ResourceTemplates, XBlock):
         """
         return False
 
-    # ================================= JSON PARSING ===========================
-    @staticmethod
-    def load_from_json(json_data, system, default_class=None, parent_xblock=None):
-        """
-        This method instantiates the correct subclass of XModuleDescriptor based
-        on the contents of json_data. It does not persist it and can create one which
-        has no usage id.
-
-        parent_xblock is used to compute inherited metadata as well as to append the new xblock.
-
-        json_data:
-        - 'location' : must have this field
-        - 'category': the xmodule category (required or location must be a Location)
-        - 'metadata': a dict of locally set metadata (not inherited)
-        - 'children': a list of children's usage_ids w/in this course
-        - 'definition':
-        - '_id' (optional): the usage_id of this. Will generate one if not given one.
-        """
-        class_ = XModuleDescriptor.load_class(
-            json_data.get('category', json_data.get('location', {}).get('category')),
-            default_class
-        )
-        return class_.from_json(json_data, system, parent_xblock)
-
-    @classmethod
-    def from_json(cls, json_data, system, parent_xblock=None):
-        """
-        Creates an instance of this descriptor from the supplied json_data.
-        This may be overridden by subclasses
-
-        json_data: A json object with the keys 'definition' and 'metadata',
-            definition: A json object with the keys 'data' and 'children'
-                data: A json value
-                children: A list of edX Location urls
-            metadata: A json object with any keys
-
-        This json_data is transformed to model_data using the following rules:
-            1) The model data contains all of the fields from metadata
-            2) The model data contains the 'children' array
-            3) If 'definition.data' is a json object, model data contains all of its fields
-               Otherwise, it contains the single field 'data'
-            4) Any value later in this list overrides a value earlier in this list
-
-        json_data:
-        - 'category': the xmodule category (required)
-        - 'metadata': a dict of locally set metadata (not inherited)
-        - 'children': a list of children's usage_ids w/in this course
-        - 'definition':
-        - '_id' (optional): the usage_id of this. Will generate one if not given one.
-        """
-        usage_id = json_data.get('_id', None)
-        if not '_inherited_metadata' in json_data and parent_xblock is not None:
-            json_data['_inherited_metadata'] = parent_xblock.xblock_kvs.get_inherited_metadata().copy()
-            json_metadata = json_data.get('metadata', {})
-            for field in inheritance.INHERITABLE_METADATA:
-                if field in json_metadata:
-                    json_data['_inherited_metadata'][field] = json_metadata[field]
-
-        new_block = system.xblock_from_json(cls, usage_id, json_data)
-        if parent_xblock is not None:
-            children = parent_xblock.children
-            children.append(new_block)
-            # trigger setter method by using top level field access
-            parent_xblock.children = children
-            # decache pending children field settings (Note, truly persisting at this point would break b/c
-            # persistence assumes children is a list of ids not actual xblocks)
-            parent_xblock.save()
-        return new_block
-
     @classmethod
     def _translate(cls, key):
         'VS[compat]'
@@ -726,6 +657,17 @@ class XModuleDescriptor(XModuleFields, HTMLSnippet, ResourceTemplates, XBlock):
             )
         )
 
+    def iterfields(self):
+        """
+        A generator for iterate over the fields of this xblock (including the ones in namespaces).
+        Example usage: [field.name for field in module.iterfields()]
+        """
+        for field in self.fields:
+            yield field
+        for namespace in self.namespaces:
+            for field in getattr(self, namespace).fields:
+                yield field
+
     @property
     def non_editable_metadata_fields(self):
         """
@@ -736,6 +678,27 @@ class XModuleDescriptor(XModuleFields, HTMLSnippet, ResourceTemplates, XBlock):
         # We are not allowing editing of xblock tag and name fields at this time (for any component).
         return [XBlock.tags, XBlock.name]
 
+    def get_explicitly_set_fields_by_scope(self, scope=Scope.content):
+        """
+        Get a dictionary of the fields for the given scope which are set explicitly on this xblock. (Including
+        any set to None.)
+        """
+        if scope == Scope.settings and hasattr(self, '_inherited_metadata'):
+            inherited_metadata = getattr(self, '_inherited_metadata')
+            result = {}
+            for field in self.iterfields():
+                if (field.scope == scope and
+                        field.name in self._model_data and
+                        field.name not in inherited_metadata):
+                    result[field.name] = self._model_data[field.name]
+            return result
+        else:
+            result = {}
+            for field in self.iterfields():
+                if (field.scope == scope and field.name in self._model_data):
+                    result[field.name] = self._model_data[field.name]
+            return result
+
     @property
     def editable_metadata_fields(self):
         """

common/test/data/splitmongo_json/definitions.json

@@ -2,7 +2,7 @@
     {
         "_id":"head12345_12",
         "category":"course",
-        "data":{
+        "fields":{
             "textbooks":[
                 
             ],
@@ -43,15 +43,17 @@
             },
             "wiki_slug":null
         },
-        "edited_by":"testassist@edx.org",
-        "edited_on":{"$date" : 1364481713238},
-        "previous_version":"head12345_11",
-        "original_version":"head12345_10"
+        "edit_info": {
+            "edited_by":"testassist@edx.org",
+            "edited_on":{"$date" : 1364481713238},
+            "previous_version":"head12345_11",
+            "original_version":"head12345_10"
+        }
     },
     {
         "_id":"head12345_11",
         "category":"course",
-        "data":{
+        "fields":{
             "textbooks":[
                 
             ],
@@ -92,15 +94,17 @@
             },
             "wiki_slug":null
         },
-        "edited_by":"testassist@edx.org",
-        "edited_on":{"$date" : 1364481713238},
-        "previous_version":"head12345_10",
-        "original_version":"head12345_10"
+        "edit_info": {
+            "edited_by":"testassist@edx.org",
+            "edited_on":{"$date" : 1364481713238},
+            "previous_version":"head12345_10",
+            "original_version":"head12345_10"
+        }
     },
     {
         "_id":"head12345_10",
         "category":"course",
-        "data":{
+        "fields":{
             "textbooks":[
                 
             ],
@@ -141,15 +145,17 @@
             },
             "wiki_slug":null
         },
-        "edited_by":"test@edx.org",
-        "edited_on":{"$date": 1364473713238},
-        "previous_version":null,
-        "original_version":"head12345_10"
+        "edit_info": {
+            "edited_by":"test@edx.org",
+            "edited_on":{"$date": 1364473713238},
+            "previous_version":null,
+            "original_version":"head12345_10"
+        }
     },
     {
         "_id":"head23456_1",
         "category":"course",
-        "data":{
+        "fields":{
             "textbooks":[
                 
             ],
@@ -190,15 +196,17 @@
             },
             "wiki_slug":null
         },
-        "edited_by":"test@edx.org",
-        "edited_on":{"$date": 1364481313238},
-        "previous_version":"head23456_0",
-        "original_version":"head23456_0"
+        "edit_info": {
+            "edited_by":"test@edx.org",
+            "edited_on":{"$date": 1364481313238},
+            "previous_version":"head23456_0",
+            "original_version":"head23456_0"
+        }
     },
     {
         "_id":"head23456_0",
         "category":"course",
-        "data":{
+        "fields":{
             "textbooks":[
                 
             ],
@@ -239,15 +247,17 @@
             },
             "wiki_slug":null
         },
-        "edited_by":"test@edx.org",
-        "edited_on":{"$date" : 1364481313238},
-        "previous_version":null,
-        "original_version":"head23456_0"
+        "edit_info": {
+            "edited_by":"test@edx.org",
+            "edited_on":{"$date" : 1364481313238},
+            "previous_version":null,
+            "original_version":"head23456_0"
+        }
     },
     {
         "_id":"head345679_1",
         "category":"course",
-        "data":{
+        "fields":{
             "textbooks":[
                 
             ],
@@ -281,54 +291,66 @@
             },
             "wiki_slug":null
         },
-        "edited_by":"test@edx.org",
-        "edited_on":{"$date" : 1364481313238},
-        "previous_version":null,
-        "original_version":"head23456_0"
+        "edit_info": {
+            "edited_by":"test@edx.org",
+            "edited_on":{"$date" : 1364481313238},
+            "previous_version":null,
+            "original_version":"head23456_0"
+        }
     },
     {
         "_id":"chapter12345_1",
         "category":"chapter",
-        "data":null,
-        "edited_by":"testassist@edx.org",
-        "edited_on":{"$date" : 1364483713238},
-        "previous_version":null,
-        "original_version":"chapter12345_1"
+        "fields":{},
+        "edit_info": {
+            "edited_by":"testassist@edx.org",
+            "edited_on":{"$date" : 1364483713238},
+            "previous_version":null,
+            "original_version":"chapter12345_1"
+        }
     },
     {
         "_id":"chapter12345_2",
         "category":"chapter",
-        "data":null,
-        "edited_by":"testassist@edx.org",
-        "edited_on":{"$date" : 1364483713238},
-        "previous_version":null,
-        "original_version":"chapter12345_2"
+        "fields":{},
+        "edit_info": {
+            "edited_by":"testassist@edx.org",
+            "edited_on":{"$date" : 1364483713238},
+            "previous_version":null,
+            "original_version":"chapter12345_2"
+        }
     },
     {
         "_id":"chapter12345_3",
         "category":"chapter",
-        "data":null,
-        "edited_by":"testassist@edx.org",
-        "edited_on":{"$date" : 1364483713238},
-        "previous_version":null,
-        "original_version":"chapter12345_3"
+        "fields":{},
+        "edit_info": {
+            "edited_by":"testassist@edx.org",
+            "edited_on":{"$date" : 1364483713238},
+            "previous_version":null,
+            "original_version":"chapter12345_3"
+        }
     },
     {
         "_id":"problem12345_3_1",
         "category":"problem",
-        "data":"",
-        "edited_by":"testassist@edx.org",
-        "edited_on":{"$date" : 1364483713238},
-        "previous_version":null,
-        "original_version":"problem12345_3_1"
+        "fields": {"data": ""},
+        "edit_info": {
+            "edited_by":"testassist@edx.org",
+            "edited_on":{"$date" : 1364483713238},
+            "previous_version":null,
+            "original_version":"problem12345_3_1"
+        }
     },
     {
         "_id":"problem12345_3_2",
         "category":"problem",
-        "data":"",
-        "edited_by":"testassist@edx.org",
-        "edited_on":{"$date" : 1364483713238},
-        "previous_version":null,
-        "original_version":"problem12345_3_2"
+        "fields": {"data": ""},
+        "edit_info": {
+            "edited_by":"testassist@edx.org",
+            "edited_on":{"$date" : 1364483713238},
+            "previous_version":null,
+            "original_version":"problem12345_3_2"
+        }
     }
 ]
\ No newline at end of file