Adding a get method to the queryset that raises exceptions if more or less than one item is returned

mongoengine/queryset.py

@@ -18,6 +18,11 @@ class InvalidQueryError(Exception):
 class OperationError(Exception):
     pass
 
+class MultipleObjectsReturned(Exception):
+    pass
+
+class DoesNotExist(Exception):
+    pass
 
 class Q(object):
     
@@ -290,6 +295,20 @@ class QuerySet(object):
 
         return mongo_query
 
+    def get(self):
+        """Retrieve the the matching object raising 
+        'MultipleObjectsReturned' or 'DoesNotExist' exceptions
+        if multiple or no results are found.
+        """
+        count = self.count()
+        if count == 1:
+            return self[0]
+        elif count > 1:
+            raise MultipleObjectsReturned
+        else:
+            raise DoesNotExist
+
+
     def first(self):
         """Retrieve the first object matching the query.
         """