conditionally adding response_data in context

common/lib/capa/capa/inputtypes.py

@@ -224,8 +224,8 @@ class InputTypeBase(object):
         self.hint = feedback.get('hint', '')
         self.hintmode = feedback.get('hintmode', None)
         self.input_state = state.get('input_state', {})
-        self.answervariable = state.get("answervariable", None)
-        self.response_data = state.get("response_data", None)
+        self.answervariable = state.get('answervariable', None)
+        self.response_data = state.get('response_data', None)
 
         # put hint above msg if it should be displayed
         if self.hintmode == 'always':
@@ -317,9 +317,12 @@ class InputTypeBase(object):
             'value': self.value,
             'status': Status(self.status, self.capa_system.i18n.ugettext),
             'msg': self.msg,
-            'STATIC_URL': self.capa_system.STATIC_URL,
-            'response_data': self.response_data
+            'STATIC_URL': self.capa_system.STATIC_URL
         }
+
+        if self.response_data is not None:
+            context['response_data'] = self.response_data
+
         context.update(
             (a, v) for (a, v) in self.loaded_attributes.iteritems() if a in self.to_render
         )