Don't save null about items to db as it chokes lms.

cms/djangoapps/contentstore/utils.py

@@ -116,3 +116,12 @@ def compute_unit_state(unit):
 
 def get_date_display(date):
     return date.strftime("%d %B, %Y at %I:%M %p")
+
+def update_item(location, value):
+    """
+    If value is None, delete the db entry. Otherwise, update it using the correct modulestore.
+    """
+    if value is None:
+        get_modulestore(location).delete_item(location)
+    else:
+        get_modulestore(location).update_item(location, value)
\ No newline at end of file

cms/djangoapps/models/settings/course_details.py

@@ -7,6 +7,7 @@ import time
 from contentstore.utils import get_modulestore
 from util.converters import jsdate_to_time, time_to_date
 from cms.djangoapps.models.settings import course_grading
+from cms.djangoapps.contentstore.utils import update_item
 
 class CourseDetails:
     def __init__(self, location):
@@ -117,16 +118,16 @@ class CourseDetails:
         # NOTE: below auto writes to the db w/o verifying that any of the fields actually changed
         # to make faster, could compare against db or could have client send over a list of which fields changed.
         temploc = Location(course_location)._replace(category='about', name='syllabus')
-        get_modulestore(temploc).update_item(temploc, jsondict['syllabus'])
+        update_item(temploc, jsondict['syllabus'])
 
         temploc = temploc._replace(name='overview')
-        get_modulestore(temploc).update_item(temploc, jsondict['overview'])
+        update_item(temploc, jsondict['overview'])
         
         temploc = temploc._replace(name='effort')
-        get_modulestore(temploc).update_item(temploc, jsondict['effort'])
+        update_item(temploc, jsondict['effort'])
         
         temploc = temploc._replace(name='video')
-        get_modulestore(temploc).update_item(temploc, jsondict['intro_video'])
+        update_item(temploc, jsondict['intro_video'])
         
                     
         # Could just generate and return a course obj w/o doing any db reads, but I put the reads in as a means to confirm