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 | None = None,
    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 | None = None,
    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 | None = None,
    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 to include the field in the __repr__ output.

eq : bool Default: True

Determines if a __eq__ method 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 a __hash__ method should be included in the class, as in dataclasses.dataclass.

frozen : bool | None Default: None

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

The Pydantic config to use for the dataclass.

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: 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.

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 rebuild the pydantic-core schema for.

force : bool Default: False

Whether to force the rebuilding of the 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 : MappingNamespace | None Default: None

The types namespace, defaults to None.

is_pydantic_dataclass

def is_pydantic_dataclass(class_: type[Any]) -> TypeGuard[type[PydanticDataclass]]

Whether a class is a pydantic dataclass.

Returns

TypeGuard[type[PydanticDataclass]] — True if the class is a pydantic dataclass, False otherwise.

Parameters

class_ : type[Any]

The class.