Add __values__ property with deprecation warning and test for it

pydantic/main.py

@@ -656,6 +656,11 @@ class BaseModel(metaclass=MetaModel):
         ret.extend(self.__dict__.keys())
         return ret
 
+    @property
+    def __values__(self) -> 'DictStrAny':
+        warnings.warn('`__values__` attribute is deprecated, use `__dict__` instead', DeprecationWarning)
+        return self.__dict__
+
 
 def create_model(
     model_name: str,

tests/test_edge_cases.py

@@ -995,3 +995,13 @@ def test_nested_init(model):
     assert m.self == 'Top Model'
     assert m.nest.self == 'Nested Model'
     assert m.nest.modified_number == 1
+
+
+def test_values_attr_deprecation():
+    class Model(BaseModel):
+        foo: int
+        bar: str
+
+    m = Model(foo=4, bar='baz')
+    with pytest.warns(DeprecationWarning, match='`__values__` attribute is deprecated, use `__dict__` instead'):
+        assert m.__values__ == m.__dict__