make export a bit more resilient. If there's a piece of metadata that we can't serialize - i.e. someone wrote a new bool attribute and didn't put it in the type mapping table - then we log the exception and continue.

cms/djangoapps/contentstore/tests/test_contentstore.py

@@ -263,7 +263,33 @@ class ContentStoreToyCourseTest(ModuleStoreTestCase):
         # note, we know the link it should be because that's what in the 'full' course in the test data
         self.assertContains(resp, '/c4x/edX/full/asset/handouts_schematic_tutorial.pdf')
 
+    def test_export_course_with_unknown_metadata(self):
+        ms = modulestore('direct')
+        cs = contentstore()
 
+        import_from_xml(ms, 'common/test/data/', ['full'])
+        location = CourseDescriptor.id_to_location('edX/full/6.002_Spring_2012')
+
+        root_dir = path(mkdtemp_clean())
+
+        course = ms.get_item(location)
+
+        # add a bool piece of unknown metadata so we can verify we don't throw an exception
+        course.metadata['new_metadata'] = True
+
+        ms.update_metadata(location, course.metadata)
+
+        print 'Exporting to tempdir = {0}'.format(root_dir)
+
+        # export out to a tempdir
+        bExported = False
+        try:
+            export_to_xml(ms, cs, location, root_dir, 'test_export')
+            bExported = True
+        except Exception:
+            pass
+
+        self.assertTrue(bExported)
 
 class ContentStoreTest(ModuleStoreTestCase):
     """

common/lib/xmodule/xmodule/xml_module.py

@@ -379,7 +379,11 @@ class XmlDescriptor(XModuleDescriptor):
             if attr not in self.metadata_to_strip and attr not in self.metadata_to_export_to_policy:
                 val = val_for_xml(attr)
                 #logging.debug('location.category = {0}, attr = {1}'.format(self.location.category, attr))
-                xml_object.set(attr, val)
+                try:
+                    xml_object.set(attr, val)
+                except Exception, e:
+                    logging.exception('Failed to serialize metadata attribute {0} with value {1}. This could mean data loss!!!  Exception: {2}'.format(attr, val, e))
+                    pass
 
         if self.export_to_file():
             # Write the definition to a file