get_document_or_404 raises 404 if given an invalid ObjectId

(and possibly on other errors, not sure what else raises
ValidationError)

mongoengine/django/shortcuts.py

@@ -1,6 +1,7 @@
 from django.http import Http404
 from mongoengine.queryset import QuerySet
 from mongoengine.base import BaseDocument
+from mongoengine.base import ValidationError
 
 def _get_queryset(cls):
     """Inspired by django.shortcuts.*"""
@@ -25,7 +26,7 @@ def get_document_or_404(cls, *args, **kwargs):
     queryset = _get_queryset(cls)
     try:
         return queryset.get(*args, **kwargs)
-    except queryset._document.DoesNotExist:
+    except (queryset._document.DoesNotExist, ValidationError):
         raise Http404('No %s matches the given query.' % queryset._document._class_name)
 
 def get_list_or_404(cls, *args, **kwargs):