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- """Provide an enhanced dataclass that performs validation."""
- from __future__ import annotations as _annotations
- import dataclasses
- import functools
- import sys
- import types
- from typing import TYPE_CHECKING, Any, Callable, Generic, Literal, NoReturn, TypeVar, overload
- from warnings import warn
- from typing_extensions import TypeGuard, dataclass_transform
- from ._internal import _config, _decorators, _mock_val_ser, _namespace_utils, _typing_extra
- from ._internal import _dataclasses as _pydantic_dataclasses
- from ._migration import getattr_migration
- from .config import ConfigDict
- from .errors import PydanticUserError
- from .fields import Field, FieldInfo, PrivateAttr
- if TYPE_CHECKING:
- from ._internal._dataclasses import PydanticDataclass
- from ._internal._namespace_utils import MappingNamespace
- __all__ = 'dataclass', 'rebuild_dataclass'
- _T = TypeVar('_T')
- if sys.version_info >= (3, 10):
- @dataclass_transform(field_specifiers=(dataclasses.field, Field, PrivateAttr))
- @overload
- def dataclass(
- *,
- init: Literal[False] = False,
- repr: bool = True,
- eq: bool = True,
- order: bool = False,
- unsafe_hash: bool = False,
- frozen: bool = False,
- config: ConfigDict | type[object] | None = None,
- validate_on_init: bool | None = None,
- kw_only: bool = ...,
- slots: bool = ...,
- ) -> Callable[[type[_T]], type[PydanticDataclass]]: # type: ignore
- ...
- @dataclass_transform(field_specifiers=(dataclasses.field, Field, PrivateAttr))
- @overload
- def dataclass(
- _cls: type[_T], # type: ignore
- *,
- init: Literal[False] = False,
- repr: bool = True,
- eq: bool = True,
- order: bool = False,
- unsafe_hash: bool = False,
- frozen: bool | None = None,
- config: ConfigDict | type[object] | None = None,
- validate_on_init: bool | None = None,
- kw_only: bool = ...,
- slots: bool = ...,
- ) -> type[PydanticDataclass]: ...
- else:
- @dataclass_transform(field_specifiers=(dataclasses.field, Field, PrivateAttr))
- @overload
- def dataclass(
- *,
- init: Literal[False] = False,
- repr: bool = True,
- eq: bool = True,
- order: bool = False,
- unsafe_hash: bool = False,
- frozen: bool | None = None,
- config: ConfigDict | type[object] | None = None,
- validate_on_init: bool | None = None,
- ) -> Callable[[type[_T]], type[PydanticDataclass]]: # type: ignore
- ...
- @dataclass_transform(field_specifiers=(dataclasses.field, Field, PrivateAttr))
- @overload
- def dataclass(
- _cls: type[_T], # type: ignore
- *,
- init: Literal[False] = False,
- repr: bool = True,
- eq: bool = True,
- order: bool = False,
- unsafe_hash: bool = False,
- frozen: bool | None = None,
- config: ConfigDict | type[object] | None = None,
- validate_on_init: bool | None = None,
- ) -> type[PydanticDataclass]: ...
- @dataclass_transform(field_specifiers=(dataclasses.field, Field, PrivateAttr))
- def dataclass(
- _cls: type[_T] | None = None,
- *,
- init: Literal[False] = False,
- repr: bool = True,
- eq: bool = True,
- order: bool = False,
- unsafe_hash: bool = False,
- frozen: bool | None = None,
- config: ConfigDict | type[object] | None = None,
- validate_on_init: bool | None = None,
- kw_only: bool = False,
- slots: bool = False,
- ) -> Callable[[type[_T]], type[PydanticDataclass]] | type[PydanticDataclass]:
- """!!! abstract "Usage Documentation"
- [`dataclasses`](../concepts/dataclasses.md)
- A decorator used to create a Pydantic-enhanced dataclass, similar to the standard Python `dataclass`,
- but with added validation.
- This function should be used similarly to `dataclasses.dataclass`.
- Args:
- _cls: The target `dataclass`.
- init: Included for signature compatibility with `dataclasses.dataclass`, and is passed through to
- `dataclasses.dataclass` when appropriate. If specified, must be set to `False`, as pydantic inserts its
- own `__init__` function.
- repr: A boolean indicating whether to include the field in the `__repr__` output.
- eq: Determines if a `__eq__` method should be generated for the class.
- order: Determines if comparison magic methods should be generated, such as `__lt__`, but not `__eq__`.
- unsafe_hash: Determines if a `__hash__` method should be included in the class, as in `dataclasses.dataclass`.
- frozen: Determines if the generated class should be a 'frozen' `dataclass`, which does not allow its
- attributes to be modified after it has been initialized. If not set, the value from the provided `config` argument will be used (and will default to `False` otherwise).
- config: The Pydantic config to use for the `dataclass`.
- validate_on_init: A deprecated parameter included for backwards compatibility; in V2, all Pydantic dataclasses
- are validated on init.
- kw_only: Determines if `__init__` method parameters must be specified by keyword only. Defaults to `False`.
- slots: Determines if the generated class should be a 'slots' `dataclass`, which does not allow the addition of
- new attributes after instantiation.
- Returns:
- A decorator that accepts a class as its argument and returns a Pydantic `dataclass`.
- Raises:
- AssertionError: Raised if `init` is not `False` or `validate_on_init` is `False`.
- """
- assert init is False, 'pydantic.dataclasses.dataclass only supports init=False'
- assert validate_on_init is not False, 'validate_on_init=False is no longer supported'
- if sys.version_info >= (3, 10):
- kwargs = {'kw_only': kw_only, 'slots': slots}
- else:
- kwargs = {}
- def create_dataclass(cls: type[Any]) -> type[PydanticDataclass]:
- """Create a Pydantic dataclass from a regular dataclass.
- Args:
- cls: The class to create the Pydantic dataclass from.
- Returns:
- A Pydantic dataclass.
- """
- from ._internal._utils import is_model_class
- if is_model_class(cls):
- raise PydanticUserError(
- f'Cannot create a Pydantic dataclass from {cls.__name__} as it is already a Pydantic model',
- code='dataclass-on-model',
- )
- original_cls = cls
- # we warn on conflicting config specifications, but only if the class doesn't have a dataclass base
- # because a dataclass base might provide a __pydantic_config__ attribute that we don't want to warn about
- has_dataclass_base = any(dataclasses.is_dataclass(base) for base in cls.__bases__)
- if not has_dataclass_base and config is not None and hasattr(cls, '__pydantic_config__'):
- warn(
- f'`config` is set via both the `dataclass` decorator and `__pydantic_config__` for dataclass {cls.__name__}. '
- f'The `config` specification from `dataclass` decorator will take priority.',
- category=UserWarning,
- stacklevel=2,
- )
- # if config is not explicitly provided, try to read it from the type
- config_dict = config if config is not None else getattr(cls, '__pydantic_config__', None)
- config_wrapper = _config.ConfigWrapper(config_dict)
- decorators = _decorators.DecoratorInfos.build(cls)
- decorators.update_from_config(config_wrapper)
- # Keep track of the original __doc__ so that we can restore it after applying the dataclasses decorator
- # Otherwise, classes with no __doc__ will have their signature added into the JSON schema description,
- # since dataclasses.dataclass will set this as the __doc__
- original_doc = cls.__doc__
- if _pydantic_dataclasses.is_stdlib_dataclass(cls):
- # Vanilla dataclasses include a default docstring (representing the class signature),
- # which we don't want to preserve.
- original_doc = None
- # We don't want to add validation to the existing std lib dataclass, so we will subclass it
- # If the class is generic, we need to make sure the subclass also inherits from Generic
- # with all the same parameters.
- bases = (cls,)
- if issubclass(cls, Generic):
- generic_base = Generic[cls.__parameters__] # type: ignore
- bases = bases + (generic_base,)
- cls = types.new_class(cls.__name__, bases)
- # Respect frozen setting from dataclass constructor and fallback to config setting if not provided
- if frozen is not None:
- frozen_ = frozen
- if config_wrapper.frozen:
- # It's not recommended to define both, as the setting from the dataclass decorator will take priority.
- warn(
- f'`frozen` is set via both the `dataclass` decorator and `config` for dataclass {cls.__name__!r}.'
- 'This is not recommended. The `frozen` specification on `dataclass` will take priority.',
- category=UserWarning,
- stacklevel=2,
- )
- else:
- frozen_ = config_wrapper.frozen or False
- # Make Pydantic's `Field()` function compatible with stdlib dataclasses. As we'll decorate
- # `cls` with the stdlib `@dataclass` decorator first, there are two attributes, `kw_only` and
- # `repr` that need to be understood *during* the stdlib creation. We do so in two steps:
- # 1. On the decorated class, wrap `Field()` assignment with `dataclass.field()`, with the
- # two attributes set (done in `as_dataclass_field()`)
- cls_anns = _typing_extra.safe_get_annotations(cls)
- for field_name in cls_anns:
- # We should look for assignments in `__dict__` instead, but for now we follow
- # the same behavior as stdlib dataclasses (see https://github.com/python/cpython/issues/88609)
- field_value = getattr(cls, field_name, None)
- if isinstance(field_value, FieldInfo):
- setattr(cls, field_name, _pydantic_dataclasses.as_dataclass_field(field_value))
- # 2. For bases of `cls` that are stdlib dataclasses, we temporarily patch their fields
- # (see the docstring of the context manager):
- with _pydantic_dataclasses.patch_base_fields(cls):
- cls = dataclasses.dataclass( # pyright: ignore[reportCallIssue]
- cls,
- # the value of init here doesn't affect anything except that it makes it easier to generate a signature
- init=True,
- repr=repr,
- eq=eq,
- order=order,
- unsafe_hash=unsafe_hash,
- frozen=frozen_,
- **kwargs,
- )
- if config_wrapper.validate_assignment:
- original_setattr = cls.__setattr__
- @functools.wraps(cls.__setattr__)
- def validated_setattr(instance: PydanticDataclass, name: str, value: Any, /) -> None:
- if frozen_:
- return original_setattr(instance, name, value) # pyright: ignore[reportCallIssue]
- inst_cls = type(instance)
- attr = getattr(inst_cls, name, None)
- if isinstance(attr, property):
- attr.__set__(instance, value)
- elif isinstance(attr, functools.cached_property):
- instance.__dict__.__setitem__(name, value)
- else:
- inst_cls.__pydantic_validator__.validate_assignment(instance, name, value)
- cls.__setattr__ = validated_setattr.__get__(None, cls) # type: ignore
- if slots and not hasattr(cls, '__setstate__'):
- # If slots is set, `pickle` (relied on by `copy.copy()`) will use
- # `__setattr__()` to reconstruct the dataclass. However, the custom
- # `__setattr__()` set above relies on `validate_assignment()`, which
- # in turn expects all the field values to be already present on the
- # instance, resulting in attribute errors.
- # As such, we make use of `object.__setattr__()` instead.
- # Note that we do so only if `__setstate__()` isn't already set (this is the
- # case if on top of `slots`, `frozen` is used).
- # Taken from `dataclasses._dataclass_get/setstate()`:
- def _dataclass_getstate(self: Any) -> list[Any]:
- return [getattr(self, f.name) for f in dataclasses.fields(self)]
- def _dataclass_setstate(self: Any, state: list[Any]) -> None:
- for field, value in zip(dataclasses.fields(self), state):
- object.__setattr__(self, field.name, value)
- cls.__getstate__ = _dataclass_getstate # pyright: ignore[reportAttributeAccessIssue]
- cls.__setstate__ = _dataclass_setstate # pyright: ignore[reportAttributeAccessIssue]
- # This is an undocumented attribute to distinguish stdlib/Pydantic dataclasses.
- # It should be set as early as possible:
- cls.__is_pydantic_dataclass__ = True
- cls.__pydantic_decorators__ = decorators # type: ignore
- cls.__doc__ = original_doc
- # Can be non-existent for dynamically created classes:
- firstlineno = getattr(original_cls, '__firstlineno__', None)
- cls.__module__ = original_cls.__module__
- if sys.version_info >= (3, 13) and firstlineno is not None:
- # As per https://docs.python.org/3/reference/datamodel.html#type.__firstlineno__:
- # Setting the `__module__` attribute removes the `__firstlineno__` item from the type’s dictionary.
- original_cls.__firstlineno__ = firstlineno
- cls.__firstlineno__ = firstlineno
- cls.__qualname__ = original_cls.__qualname__
- cls.__pydantic_fields_complete__ = classmethod(_pydantic_fields_complete)
- cls.__pydantic_complete__ = False # `complete_dataclass` will set it to `True` if successful.
- # TODO `parent_namespace` is currently None, but we could do the same thing as Pydantic models:
- # fetch the parent ns using `parent_frame_namespace` (if the dataclass was defined in a function),
- # and possibly cache it (see the `__pydantic_parent_namespace__` logic for models).
- _pydantic_dataclasses.complete_dataclass(cls, config_wrapper, raise_errors=False)
- return cls
- return create_dataclass if _cls is None else create_dataclass(_cls)
- def _pydantic_fields_complete(cls: type[PydanticDataclass]) -> bool:
- """Return whether the fields where successfully collected (i.e. type hints were successfully resolves).
- This is a private property, not meant to be used outside Pydantic.
- """
- return all(field_info._complete for field_info in cls.__pydantic_fields__.values())
- __getattr__ = getattr_migration(__name__)
- if sys.version_info < (3, 11):
- # Monkeypatch dataclasses.InitVar so that typing doesn't error if it occurs as a type when evaluating type hints
- # Starting in 3.11, typing.get_type_hints will not raise an error if the retrieved type hints are not callable.
- def _call_initvar(*args: Any, **kwargs: Any) -> NoReturn:
- """This function does nothing but raise an error that is as similar as possible to what you'd get
- if you were to try calling `InitVar[int]()` without this monkeypatch. The whole purpose is just
- to ensure typing._type_check does not error if the type hint evaluates to `InitVar[<parameter>]`.
- """
- raise TypeError("'InitVar' object is not callable")
- dataclasses.InitVar.__call__ = _call_initvar
- def rebuild_dataclass(
- cls: type[PydanticDataclass],
- *,
- force: bool = False,
- raise_errors: bool = True,
- _parent_namespace_depth: int = 2,
- _types_namespace: MappingNamespace | None = None,
- ) -> bool | None:
- """Try to rebuild the pydantic-core schema for the dataclass.
- This may be necessary when one of the annotations is a ForwardRef which could not be resolved during
- the initial attempt to build the schema, and automatic rebuilding fails.
- This is analogous to `BaseModel.model_rebuild`.
- Args:
- cls: The class to rebuild the pydantic-core schema for.
- force: Whether to force the rebuilding of the schema, defaults to `False`.
- raise_errors: Whether to raise errors, defaults to `True`.
- _parent_namespace_depth: The depth level of the parent namespace, defaults to 2.
- _types_namespace: The types namespace, defaults to `None`.
- Returns:
- Returns `None` if the schema is already "complete" and rebuilding was not required.
- If rebuilding _was_ required, returns `True` if rebuilding was successful, otherwise `False`.
- """
- if not force and cls.__pydantic_complete__:
- return None
- for attr in ('__pydantic_core_schema__', '__pydantic_validator__', '__pydantic_serializer__'):
- if attr in cls.__dict__ and not isinstance(getattr(cls, attr), _mock_val_ser.MockValSer):
- # Deleting the validator/serializer is necessary as otherwise they can get reused in
- # pydantic-core. Same applies for the core schema that can be reused in schema generation.
- delattr(cls, attr)
- cls.__pydantic_complete__ = False
- if _types_namespace is not None:
- rebuild_ns = _types_namespace
- elif _parent_namespace_depth > 0:
- rebuild_ns = _typing_extra.parent_frame_namespace(parent_depth=_parent_namespace_depth, force=True) or {}
- else:
- rebuild_ns = {}
- ns_resolver = _namespace_utils.NsResolver(
- parent_namespace=rebuild_ns,
- )
- return _pydantic_dataclasses.complete_dataclass(
- cls,
- _config.ConfigWrapper(cls.__pydantic_config__, check=False),
- raise_errors=raise_errors,
- ns_resolver=ns_resolver,
- # We could provide a different config instead (with `'defer_build'` set to `True`)
- # of this explicit `_force_build` argument, but because config can come from the
- # decorator parameter or the `__pydantic_config__` attribute, `complete_dataclass`
- # will overwrite `__pydantic_config__` with the provided config above:
- _force_build=True,
- )
- def is_pydantic_dataclass(class_: type[Any], /) -> TypeGuard[type[PydanticDataclass]]:
- """Whether a class is a pydantic dataclass.
- Args:
- class_: The class.
- Returns:
- `True` if the class is a pydantic dataclass, `False` otherwise.
- """
- try:
- return '__is_pydantic_dataclass__' in class_.__dict__ and dataclasses.is_dataclass(class_)
- except AttributeError:
- return False
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