Make StringyInteger and StringyFloat return None when they can't parse the string from json, and don't try to overwrite max_attempts if it's ''

common/lib/xmodule/xmodule/capa_module.py

@@ -32,7 +32,7 @@ class StringyInteger(Integer):
         try:
             return int(value)
         except:
-            return value
+            return None
 
 
 class StringyFloat(Float):
@@ -43,7 +43,7 @@ class StringyFloat(Float):
         try:
             return float(value)
         except:
-            return value
+            return None
 
 
 # Generated this many different variants of problems with rerandomize=per_student
@@ -140,9 +140,6 @@ class CapaModule(CapaFields, XModule):
                 # see comment on randomization_bin
                 self.seed = randomization_bin(system.seed, self.location.url)
 
-        if self.max_attempts == '':
-            self.max_attempts = None
-
         # Need the problem location in openendedresponse to send out.  Adding
         # it to the system here seems like the least clunky way to get it
         # there.
@@ -391,7 +388,7 @@ class CapaModule(CapaFields, XModule):
 
         content = {'name': self.display_name_with_default,
                    'html': html,
-                   'weight': self.descriptor.weight,
+                   'weight': self.weight,
                    }
 
         context = {'problem': content,