pydantic.dataclasses

Provide an enhanced dataclass that performs validation.

dataclass

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]]
def dataclass(
    _cls: type[_T],
    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 = ...,
) -> type[PydanticDataclass]
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,
) -> Callable[[type[_T]], type[PydanticDataclass]]
def dataclass(
    _cls: type[_T],
    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,
) -> type[PydanticDataclass]

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.

Returns

Callable[[type[_T]], type[PydanticDataclass]] | type[PydanticDataclass] — A decorator that accepts a class as its argument and returns a Pydantic dataclass.

Parameters

_cls : type[_T] | None Default: None

The target dataclass.

init : Literal[False] Default: False

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 : bool Default: True

A boolean indicating whether or not to include the field in the __repr__ output.

eq : bool Default: True

Determines if a __eq__ should be generated for the class.

order : bool Default: False

Determines if comparison magic methods should be generated, such as __lt__, but not __eq__.

unsafe_hash : bool Default: False

Determines if an unsafe hashing function should be included in the class.

frozen : bool Default: False

Determines if the generated class should be a ‘frozen’ dataclass, which does not allow its attributes to be modified from its constructor.

config : ConfigDict | type[object] | None Default: None

A configuration for the dataclass generation.

validate_on_init : bool | None Default: None

A deprecated parameter included for backwards compatibility; in V2, all Pydantic dataclasses are validated on init.

kw_only : bool Default: False

Determines if __init__ method parameters must be specified by keyword only. Defaults to False.

slots : bool Default: False

Determines if the generated class should be a ‘slots’ dataclass, which does not allow the addition of new attributes after instantiation.

Raises

• AssertionError — Raised if init is not False or validate_on_init is False.

rebuild_dataclass

def rebuild_dataclass(
    cls: type[PydanticDataclass],
    force: bool = False,
    raise_errors: bool = True,
    _parent_namespace_depth: int = 2,
    _types_namespace: dict[str, Any] | 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.

Returns

bool | None — Returns None if the schema is already “complete” and rebuilding was not required. bool | None — If rebuilding was required, returns True if rebuilding was successful, otherwise False.

Parameters

cls : type[PydanticDataclass]

The class to build the dataclass core schema for.

force : bool Default: False

Whether to force the rebuilding of the model schema, defaults to False.

raise_errors : bool Default: True

Whether to raise errors, defaults to True.

_parent_namespace_depth : int Default: 2

The depth level of the parent namespace, defaults to 2.

_types_namespace : dict[str, Any] | None Default: None

The types namespace, defaults to None.