better multi prop

Author: dnwpark

gel/_internal/_qbmodel/_pydantic/_fields.py

@@ -285,16 +285,25 @@ def _validate(
     ):
         lt: type[_tracked_list.DowncastingTrackedList[_ST_co, _BT_co]] = (
             _tracked_list.DowncastingTrackedList[
-                generic_args[0],
-                generic_args[1],
+                generic_args[0],  # type: ignore [valid-type]
+                generic_args[1],  # type: ignore [valid-type]
             ]
         )
-        if isinstance(value, _tracked_list.DefaultList):
-            # Convert the pydantic generated default into
-            # the internal DEFAULT_VALUE
-            return _abstract.DEFAULT_VALUE
 
-        return LinkSet.__gel_validate__(lt, value)
+        # If the value wasn't explicitly provided by a user, pydantic will
+        # generate a DefaultList. __gel_validate__ will then create the
+        # appropriate tracked list.
+        lst = LinkSet.__gel_validate__(lt, value)
+
+        if isinstance(value, _tracked_list.DefaultList):
+            # GelSourceModel will do its best to set tracking flags, but set
+            # the here just in case.
+            #
+            # eg. __init__ will call this
+            lst._mode = _tracked_list.Mode.Write
+            lst.__gel_overwrite_data__ = False
+
+        return lst
 
 
 class _ComputedMultiProperty(

gel/_internal/_save.py

@@ -40,8 +40,9 @@
 from gel._internal._tracked_list import (
     AbstractCollection,
     AbstractTrackedList,
-    TrackedList,
     DowncastingTrackedList,
+    Mode,
+    TrackedList,
 )
 from gel._internal._edgeql import PointerKind, quote_ident
 
@@ -822,7 +823,21 @@ def make_plan(
                     (mp_added := val.__gel_get_added__())
                     # Even if there are no added values, push the change if
                     # there is a default value we want to override.
-                    or (is_new and prop.has_default)
+                    or (
+                        is_new
+                        and prop.has_default
+                        and not (
+                            # Pydantic should ensure unset tracked lists will
+                            # have these flags.
+                            # We do this in:
+                            # - GelSourceModel.model_construct
+                            # - GelSourceModel.__getattr__
+                            # - GelSourceModel.__init__
+                            #   - via _MultiProperty._validate
+                            val._mode == Mode.Write
+                            and not val.__gel_overwrite_data__
+                        )
+                    )
                 ):
                     push_change(
                         requireds,