Dataclass extra

changes/3393-DetachHead.md

@@ -0,0 +1 @@
+dataclasses now support the `extra` config option

pydantic/dataclasses.py

@@ -1,10 +1,10 @@
-from typing import TYPE_CHECKING, Any, Callable, Dict, Optional, Type, TypeVar, Union, overload
+from typing import TYPE_CHECKING, Any, Callable, Dict, Optional, Type, TypeVar, Union, get_type_hints, overload
 
 from .class_validators import gather_all_validators
 from .error_wrappers import ValidationError
 from .errors import DataclassTypeError
 from .fields import Field, FieldInfo, Required, Undefined
-from .main import create_model, validate_model
+from .main import Extra, create_model, validate_model
 from .typing import resolve_annotations
 from .utils import ClassAttribute
 
@@ -188,6 +188,15 @@ def _process_class(
         cls.__name__, __config__=config, __module__=_cls.__module__, __validators__=validators, **field_definitions
     )
 
+    if getattr(config, 'extra', Extra.forbid) is not Extra.forbid:
+        def allow_extra_init(self, *args, **kwargs):
+            self.__original_init__(*args, **{
+                k: v for k, v in kwargs.items() if k in get_type_hints(type(self))
+            })
+
+        cls.__original_init__ = cls.__init__
+        cls.__init__ = allow_extra_init
+
     cls.__initialised__ = False
     cls.__validate__ = classmethod(_validate_dataclass)  # type: ignore[assignment]
     cls.__get_validators__ = classmethod(_get_validators)  # type: ignore[assignment]

tests/test_dataclasses.py

@@ -8,7 +8,7 @@
 import pytest
 
 import pydantic
-from pydantic import BaseModel, ValidationError, validator
+from pydantic import BaseModel, Extra, ValidationError, validator
 
 
 def test_simple():
@@ -945,3 +945,30 @@ def __new__(cls, *args, **kwargs):
         instance = cls(a=test_string)
         assert instance._special_property == 1
         assert instance.a == test_string
+
+
+def test_allow_extra():
+    class C:
+        extra = Extra.ignore
+
+    @pydantic.dataclasses.dataclass(config=C)
+    class Foo:
+        a: str
+        b: str
+
+    Foo(**{"a": "bar", "b": "foo", "c": 1})
+
+
+def test_allow_extra_subclass():
+    class C:
+        extra = Extra.ignore
+
+    @pydantic.dataclasses.dataclass(config=C)
+    class Foo:
+        a: str
+
+    @pydantic.dataclasses.dataclass(config=C)
+    class Bar(Foo):
+        b: str
+
+    Bar(**{"a": "bar", "b": "foo", "c": 1})