From 652e2aa24c1d8795a65afd50174216bdcda2a219 Mon Sep 17 00:00:00 2001
From: Victor Shnayder <victor@mitx.mit.edu>
Date: Wed, 1 Aug 2012 19:22:14 -0400
Subject: [PATCH] fix for inheriting metadata bug

* problem was on import to json--got all the metadata,
  but didn't preserve the _inherited_metadata
* added own_metadata property, use it instead
---
 common/lib/xmodule/xmodule/modulestore/xml.py          | 3 +++
 common/lib/xmodule/xmodule/modulestore/xml_importer.py | 4 +++-
 common/lib/xmodule/xmodule/x_module.py                 | 8 ++++++++
 3 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/common/lib/xmodule/xmodule/modulestore/xml.py b/common/lib/xmodule/xmodule/modulestore/xml.py
index e7f9c9ce0a..d6540023e8 100644
--- a/common/lib/xmodule/xmodule/modulestore/xml.py
+++ b/common/lib/xmodule/xmodule/modulestore/xml.py
@@ -41,6 +41,9 @@ class ImportSystem(XMLParsingSystem, MakoDescriptorSystem):
         self.used_slugs = set()
 
         def process_xml(xml):
+            """Takes an xml string, and returns a XModuleDescriptor created from
+            that xml.
+            """
             try:
                 # VS[compat]
                 # TODO (cpennington): Remove this once all fall 2012 courses
diff --git a/common/lib/xmodule/xmodule/modulestore/xml_importer.py b/common/lib/xmodule/xmodule/modulestore/xml_importer.py
index 578ade95fe..891db7e994 100644
--- a/common/lib/xmodule/xmodule/modulestore/xml_importer.py
+++ b/common/lib/xmodule/xmodule/modulestore/xml_importer.py
@@ -35,6 +35,8 @@ def import_from_xml(store, data_dir, course_dirs=None, eager=True,
             store.update_item(module.location, module.definition['data'])
         if 'children' in module.definition:
             store.update_children(module.location, module.definition['children'])
-        store.update_metadata(module.location, dict(module.metadata))
+        # NOTE: It's important to use own_metadata here to avoid writing
+        # inherited metadata everywhere.
+        store.update_metadata(module.location, dict(module.own_metadata))
 
     return module_store
diff --git a/common/lib/xmodule/xmodule/x_module.py b/common/lib/xmodule/xmodule/x_module.py
index 2a1769bbd7..360f1b07d0 100644
--- a/common/lib/xmodule/xmodule/x_module.py
+++ b/common/lib/xmodule/xmodule/x_module.py
@@ -358,6 +358,14 @@ class XModuleDescriptor(Plugin, HTMLSnippet):
         self._child_instances = None
         self._inherited_metadata = set()
 
+    @property
+    def own_metadata(self):
+        """
+        Return the metadata that is not inherited, but was defined on this module.
+        """
+        return dict((k,v) for k,v in self.metadata.items()
+                    if k not in self._inherited_metadata)
+
     def inherit_metadata(self, metadata):
         """
         Updates this module with metadata inherited from a containing module.