pydantic · dmontagu · Jul 5, 2023 · Jul 5, 2023 · Jul 5, 2023
diff --git a/changes/6457-dmontagu.md b/changes/6457-dmontagu.md
@@ -0,0 +1 @@
+Fix bug where round-trip pickling/unpickling a `RootModel` would change the value of `__dict__`.
diff --git a/pydantic/main.py b/pydantic/main.py
@@ -782,10 +782,10 @@ def __getstate__(self) -> dict[Any, Any]:
         }
 
     def __setstate__(self, state: dict[Any, Any]) -> None:
-        _object_setattr(self, '__dict__', state['__dict__'])
         _object_setattr(self, '__pydantic_fields_set__', state['__pydantic_fields_set__'])
         _object_setattr(self, '__pydantic_extra__', state['__pydantic_extra__'])
         _object_setattr(self, '__pydantic_private__', state['__pydantic_private__'])
+        _object_setattr(self, '__dict__', state['__dict__'])
 
     def __eq__(self, other: Any) -> bool:
         if isinstance(other, BaseModel):

diff --git a/tests/test_root_model.py b/tests/test_root_model.py
@@ -1,3 +1,4 @@
+import pickle
 from typing import Any, Dict, List, Optional, Union
 
 import pytest
@@ -548,3 +549,15 @@ class BModel(BaseModel):
         match='"RootModel.__init__" accepts either a single positional argument or arbitrary keyword arguments',
     ):
         Model({'value': 42}, other_value='abc')
+
+
+def test_pickle_root_model(create_module):
+    @create_module
+    def module():
+        from pydantic import RootModel
+
+        class MyRootModel(RootModel[str]):
+            pass
+
+    MyRootModel = module.MyRootModel
+    assert MyRootModel(root='abc') == pickle.loads(pickle.dumps(MyRootModel(root='abc')))
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1 @@
		Fix bug where round-trip pickling/unpickling a `RootModel` would change the value of `__dict__`.