Handle contents not editable by users on the server

Relates to MS-589

server/books/schema/inputs.py

@@ -13,6 +13,7 @@ class InputTypes(graphene.Enum):
     document_block = 'document_block'
     content_list_item = 'content_list_item'
     subtitle = 'subtitle'
+    readonly = 'readonly'
 
 
 class ContentElementValueInput(InputObjectType):

server/books/schema/mutations/contentblock.py

@@ -48,7 +48,7 @@ class MutateContentBlock(relay.ClientIDMutation):
                 content_block.title = title
 
             if contents is not None:
-                content_block.contents = json.dumps([handle_content_block(c, info.context, module) for c in contents])
+                content_block.contents = json.dumps([handle_content_block(c, info.context, module, previous_contents=content_block.contents) for c in contents if c is not None])
 
             content_block.save()
 

server/books/schema/mutations/utils.py

@@ -41,10 +41,11 @@ ALLOWED_BLOCKS = (
     'document_block',
     'content_list_item',
     'subtitle',
+    'readonly'
 )
 
 
-def handle_content_block(content, context=None, module=None, allowed_blocks=ALLOWED_BLOCKS):
+def handle_content_block(content, context=None, module=None, allowed_blocks=ALLOWED_BLOCKS, previous_contents=None):
     # todo: add all the content blocks
     # todo: sanitize user inputs!
     if content['type'] not in allowed_blocks:
@@ -64,9 +65,10 @@ def handle_content_block(content, context=None, module=None, allowed_blocks=ALLO
         value = content['value']
         if value.get('id') is not None:
             assignment = get_object(Assignment, value.get('id'))
-            assignment.title = value.get('title')
+            if assignment.user_created and assignment.owner == context.user:
-            assignment.assignment = value.get('assignment')
+                assignment.title = value.get('title')
-            assignment.save()
+                assignment.assignment = value.get('assignment')
+                assignment.save()
         else:
             assignment = Assignment.objects.create(
                 title=value.get('title'),
@@ -119,7 +121,12 @@ def handle_content_block(content, context=None, module=None, allowed_blocks=ALLO
             'type': 'content_list_item',
             'value': [handle_content_block(c, context, module) for c in content['contents']]
         }
-
+    elif content['type'] == 'readonly' and previous_contents is not None:
+        # get first item that matches the id
+        # users can re-order readonly items, but we won't let them change them otherwise, so we just take the
+        # item from before and ignore anything else
+        previous_content = next((c for c in previous_contents.raw_data if c['id'] == content['id']), None)
+        return previous_content
 
     return None