Add Draft module store that is used whenever any item is update in the CAS (but not during import, and not for templates)

cms/djangoapps/contentstore/management/commands/import.py

@@ -26,4 +26,4 @@ class Command(BaseCommand):
         print "Importing.  Data_dir={data}, course_dirs={courses}".format(
             data=data_dir,
             courses=course_dirs)
-        import_from_xml(modulestore(), data_dir, course_dirs, load_error_modules=False)
+        import_from_xml(modulestore('direct'), data_dir, course_dirs, load_error_modules=False)

cms/envs/dev.py

@@ -14,17 +14,23 @@ LOGGING = get_logger_config(ENV_ROOT / "log",
                             tracking_filename="tracking.log",
                             debug=True)
 
+modulestore_options = {
+    'default_class': 'xmodule.raw_module.RawDescriptor',
+    'host': 'localhost',
+    'db': 'xmodule',
+    'collection': 'modulestore',
+    'fs_root': GITHUB_REPO_ROOT,
+    'render_template': 'mitxmako.shortcuts.render_to_string',
+}
+
 MODULESTORE = {
     'default': {
+        'ENGINE': 'xmodule.modulestore.mongo.DraftMongoModuleStore',
+        'OPTIONS': modulestore_options
+    },
+    'direct': {
         'ENGINE': 'xmodule.modulestore.mongo.MongoModuleStore',
-        'OPTIONS': {
-            'default_class': 'xmodule.raw_module.RawDescriptor',
-            'host': 'localhost',
-            'db': 'xmodule',
-            'collection': 'modulestore',
-            'fs_root': GITHUB_REPO_ROOT,
-            'render_template': 'mitxmako.shortcuts.render_to_string',
-        }
+        'OPTIONS': modulestore_options
     }
 }
 

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

@@ -345,7 +345,9 @@ class ModuleStore(object):
         Returns a list containing the top level XModuleDescriptors of the courses
         in this modulestore.
         '''
-        raise NotImplementedError
+        # TODO (vshnayder): Why do I have to specify i4x here?
+        course_filter = Location("i4x", category="course")
+        return self.get_items(course_filter)
 
     def get_parent_locations(self, location):
         '''Find all locations that are the parents of this location.  Needed

common/lib/xmodule/xmodule/modulestore/draft.py

@@ -0,0 +1,128 @@
+
+from . import ModuleStoreBase, Location
+from .exceptions import ItemNotFoundError
+
+
+class DraftModuleStore(ModuleStoreBase):
+    """
+    This mixin modifies a modulestore to give it draft semantics.
+    That is, edits made to units are stored to locations that have the revision 'draft',
+    and when reads are made, they first read with revision 'draft', and then fall back
+    to the baseline revision only if 'draft' doesn't exist.
+
+    This module also includes functionality to promote 'draft' modules (and optionally
+    their children) to published modules.
+    """
+
+    def get_item(self, location, depth=0):
+        """
+        Returns an XModuleDescriptor instance for the item at location.
+        If location.revision is None, returns the item with the most
+        recent revision
+
+        If any segment of the location is None except revision, raises
+            xmodule.modulestore.exceptions.InsufficientSpecificationError
+
+        If no object is found at that location, raises
+            xmodule.modulestore.exceptions.ItemNotFoundError
+
+        location: Something that can be passed to Location
+
+        depth (int): An argument that some module stores may use to prefetch
+            descendents of the queried modules for more efficient results later
+            in the request. The depth is counted in the number of calls to
+            get_children() to cache. None indicates to cache all descendents
+        """
+        try:
+            return super(DraftModuleStore, self).get_item(Location(location)._replace(revision='draft'), depth)
+        except ItemNotFoundError:
+            return super(DraftModuleStore, self).get_item(location, depth)
+
+    def get_instance(self, course_id, location):
+        """
+        Get an instance of this location, with policy for course_id applied.
+        TODO (vshnayder): this may want to live outside the modulestore eventually
+        """
+        try:
+            return super(DraftModuleStore, self).get_instance(course_id, Location(location)._replace(revision='draft'))
+        except ItemNotFoundError:
+            return super(DraftModuleStore, self).get_instance(course_id, location)
+
+    def get_items(self, location, depth=0):
+        """
+        Returns a list of XModuleDescriptor instances for the items
+        that match location. Any element of location that is None is treated
+        as a wildcard that matches any value
+
+        location: Something that can be passed to Location
+
+        depth: An argument that some module stores may use to prefetch
+            descendents of the queried modules for more efficient results later
+            in the request. The depth is counted in the number of calls to
+            get_children() to cache. None indicates to cache all descendents
+        """
+        draft_loc = Location(location)._replace(revision='draft')
+        draft_items = super(DraftModuleStore, self).get_items(draft_loc, depth)
+        items = super(DraftModuleStore, self).get_items(location, depth)
+
+        draft_locs_found = set(item.location._replace(revision=None) for item in draft_items)
+        non_draft_items = [
+            item
+            for item in items
+            if (item.location.revision != 'draft'
+                and item.location._replace(revision=None) not in draft_locs_found)
+        ]
+        return draft_items + non_draft_items
+
+    def clone_item(self, source, location):
+        """
+        Clone a new item that is a copy of the item at the location `source`
+        and writes it to `location`
+        """
+        return super(DraftModuleStore, self).clone_item(source, Location(location)._replace(revision='draft'))
+
+    def update_item(self, location, data):
+        """
+        Set the data in the item specified by the location to
+        data
+
+        location: Something that can be passed to Location
+        data: A nested dictionary of problem data
+        """
+        return super(DraftModuleStore, self).update_item(Location(location)._replace(revision='draft'), data)
+
+    def update_children(self, location, children):
+        """
+        Set the children for the item specified by the location to
+        children
+
+        location: Something that can be passed to Location
+        children: A list of child item identifiers
+        """
+        return super(DraftModuleStore, self).update_children(Location(location)._replace(revision='draft'), children)
+
+    def update_metadata(self, location, metadata):
+        """
+        Set the metadata for the item specified by the location to
+        metadata
+
+        location: Something that can be passed to Location
+        metadata: A nested dictionary of module metadata
+        """
+        return super(DraftModuleStore, self).update_metadata(Location(location)._replace(revision='draft'), metadata)
+
+    def delete_item(self, location):
+        """
+        Delete an item from this modulestore
+
+        location: Something that can be passed to Location
+        """
+        return super(DraftModuleStore, self).delete_item(Location(location)._replace(revision='draft'))
+
+    def get_parent_locations(self, location):
+        '''Find all locations that are the parents of this location.  Needed
+        for path_to_location().
+
+        returns an iterable of things that can be passed to Location.
+        '''
+        return super(DraftModuleStore, self).get_parent_locations(Location(location)._replace(revision='draft'))

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

@@ -13,6 +13,7 @@ from xmodule.mako_module import MakoDescriptorSystem
 from xmodule.error_module import ErrorDescriptor
 
 from . import ModuleStoreBase, Location
+from .draft import DraftModuleStore
 from .exceptions import (ItemNotFoundError,
                          DuplicateItemError)
 
@@ -341,3 +342,8 @@ class MongoModuleStore(ModuleStoreBase):
         are loaded on demand, rather than up front
         """
         return {}
+
+
+# DraftModuleStore is first, because it needs to intercept calls to MongoModuleStore
+class DraftMongoModuleStore(DraftModuleStore, MongoModuleStore):
+    pass

common/lib/xmodule/xmodule/templates.py

@@ -75,6 +75,6 @@ def update_templates():
                 ), exc_info=True)
                 continue
 
-            modulestore().update_item(template_location, template.data)
-            modulestore().update_children(template_location, template.children)
-            modulestore().update_metadata(template_location, template.metadata)
+            modulestore('direct').update_item(template_location, template.data)
+            modulestore('direct').update_children(template_location, template.children)
+            modulestore('direct').update_metadata(template_location, template.metadata)