Fix ValueConflictValidator

Author: jochenklar

rdmo/projects/validators.py

@@ -58,11 +58,15 @@ def __call__(self, data, serializer):
                 'set_index': data.get('set_index')
             }
 
+
             # check the widget type, which is provided with the post request
             widget_type = serializer.context['view'].request.data.get('widget_type')
             if widget_type == 'checkbox':
                 # for checkboxes, fail if a value with the same option exist
-                get_kwargs['option'] = data.get('option')
+                if data.get('option'):
+                    get_kwargs['option'] = data.get('option')
+                if data.get('external_id'):
+                    get_kwargs['external_id'] = data.get('external_id')
             else:
                 # for all other widget_types, fail if a value with the same collection_index exist
                 get_kwargs['collection_index'] = data.get('collection_index')