Make use of the new optional enforce_type flag

mentoring/mentoring.py

@@ -69,11 +69,12 @@ class MentoringBlock(XBlockWithLightChildren):
                                  default=False, scope=Scope.content)
     display_submit = Boolean(help="Allow to submit current block?", default=True, scope=Scope.content)
     xml_content = String(help="XML content", default='', scope=Scope.content)
-    weight = Float(help="Defines the maximum total grade of the block.", default=1, scope=Scope.content)
+    weight = Float(help="Defines the maximum total grade of the block.",
+                   default=1, scope=Scope.content, enforce_type=True)
     num_attempts = Integer(help="Number of attempts a user has answered for this questions",
-                           default=0, scope=Scope.user_state)
+                           default=0, scope=Scope.user_state, enforce_type=True)
     max_attempts = Integer(help="Number of max attempts for this questions", default=0,
-                           scope=Scope.content)
+                           scope=Scope.content, enforce_type=True)
     icon_class = 'problem'
     has_score = True