Set columns project when a query does not use default columns.

Author: WaVEV

django_mongodb/compiler.py

@@ -27,7 +27,9 @@ def execute_sql(
         columns = self.get_columns()
         try:
             # Avoid $project fields in case of query.annotations is not defined.
-            query = self.build_query(columns if self.query.annotations else None)
+            query = self.build_query(
+                columns if self.query.annotations or not self.query.default_cols else None
+            )
         except EmptyResultSet:
             return iter([]) if result_type == MULTI else None