Ticket #16649: save_no_select.diff

django/db/models/base.py

@@ -515 +515 @@
         if not meta.proxy:
             non_pks = [f for f in meta.local_fields if not f.primary_key]
 
-            # First, try an UPDATE. If that doesn't update anything, do an INSERT.
             pk_val = self._get_pk_val(meta)
             pk_set = pk_val is not None
-            record_exists = True
+            record_exists = False
             manager = cls._base_manager
-            if pk_set:
-                # Determine whether a record with the primary key already exists.
-                if (force_update or (not force_insert and
-                        manager.using(using).filter(pk=pk_val).exists())):
-                    # It does already exist, so do an UPDATE.
-                    if force_update or non_pks:
-                        values = [(f, None, (raw and getattr(self, f.attname) or f.pre_save(self, False))) for f in non_pks]
-                        rows = manager.using(using).filter(pk=pk_val)._update(values)
-                        if force_update and not rows:
-                            raise DatabaseError("Forced update did not affect any rows.")
-                else:
-                    record_exists = False
+            if pk_set and not force_insert:
+                # Try to update the object. If something is updated, we know the record
+                # existed. If not, we know it did not exists.
+                if force_update or non_pks:
+                    values = [(f, None, (raw and getattr(self, f.attname) or f.pre_save(self, False))) for f in non_pks]
+                    rows = manager.using(using).filter(pk=pk_val)._update(values)
+                    if rows:
+                        record_exists = True
+                    if not rows and force_update:
+                        raise DatabaseError("Forced update did not affect any rows.")
+                        
+                elif not non_pks:
+                    # There are no other fields than the pk in the model. In this case we do
+                    # not check the existense by update
+                    if manager.using(using).filter(pk=pk_val).exists():
+                        record_exists = True
             if not pk_set or not record_exists:
                 if meta.order_with_respect_to:
                     # If this is a model with an order_with_respect_to