Make default value for format setting None, and force lms and cms to be explicit…

Make default value for format setting None, and force lms and cms to be explicit about a string default

cms/djangoapps/models/settings/course_grading.py

@@ -213,7 +213,7 @@ class CourseGradingModel(object):
 
         descriptor = get_modulestore(location).get_item(location)
         return {
-                "graderType": descriptor.lms.format or 'Not Graded',
+                "graderType": descriptor.lms.format if descriptor.lms.format is not None else 'Not Graded',
                 "location": location,
                 "id": 99   # just an arbitrary value to
                 }

cms/templates/edit_subsection.html

@@ -70,7 +70,7 @@
     <div class="row gradable">
       <label>Graded as:</label>
 
-    <div class="gradable-status" data-initial-status="${subsection.lms.format if subsection.lms.format is None else 'Not Graded'}">
+    <div class="gradable-status" data-initial-status="${subsection.lms.format if subsection.lms.format is not None else 'Not Graded'}">
     </div>
 
     <div class="due-date-input row">

common/lib/xmodule/xmodule/course_module.py

@@ -592,7 +592,7 @@ class CourseDescriptor(SequenceDescriptor):
                     # The xmoduledescriptors included here are only the ones that have scores.
                     section_description = {'section_descriptor': s, 'xmoduledescriptors': filter(lambda child: child.has_score, xmoduledescriptors)}
 
-                    section_format = s.lms.format
+                    section_format = s.lms.format if s.lms.format is not None else ''
                     graded_sections[section_format] = graded_sections.get(section_format, []) + [section_description]
 
                     all_descriptors.extend(xmoduledescriptors)

lms/djangoapps/courseware/grades.py

@@ -317,7 +317,7 @@ def progress_summary(student, request, course, model_data_cache):
             section_total, graded_total = graders.aggregate_scores(
                 scores, section_module.display_name_with_default)
 
-            format = section_module.lms.format
+            format = section_module.lms.format if section_module.lms.format is not None else ''
             sections.append({
                 'display_name': section_module.display_name_with_default,
                 'url_name': section_module.url_name,

lms/djangoapps/courseware/module_render.py

@@ -103,7 +103,7 @@ def toc_for_course(user, request, course, active_chapter, active_section, model_
             if not section.lms.hide_from_toc:
                 sections.append({'display_name': section.display_name_with_default,
                                  'url_name': section.url_name,
-                                 'format': section.lms.format,
+                                 'format': section.lms.format if section.lms.format is not None else '',
                                  'due': section.lms.due,
                                  'active': active,
                                  'graded': section.lms.graded,

lms/xmodule_namespace.py

@@ -24,7 +24,6 @@ class LmsNamespace(Namespace):
         help="What format this module is in (used for deciding which "
              "grader to apply, and what to show in the TOC)",
         scope=Scope.settings,
-        default='',
     )
 
     start = Date(help="Start time when this module is visible", scope=Scope.settings)