FieldInfo

This class holds information about a field.

FieldInfo is used for any field definition regardless of whether the [Field()][pydantic.fields.Field] function is explicitly used.

Attributes

Attribute	Type	Description
annotation	`type[Any]	None`
default	Any	The default value of the field.
default_factory	`Callable[[], Any]	Callable[[dict[str, Any]], Any]
alias	`str	None`
alias_priority	`int	None`
validation_alias	`str	AliasPath
serialization_alias	`str	None`
title	`str	None`
field_title_generator	`Callable[[str, FieldInfo], str]	None`
description	`str	None`
examples	`list[Any]	None`
exclude	`bool	None`
exclude_if	`Callable[[Any], bool]	None`
discriminator	`str	types.Discriminator
deprecated	`Deprecated	str
json_schema_extra	`JsonDict	Callable[[JsonDict], None]
frozen	`bool	None`
validate_default	`bool	None`
repr	bool	Whether to include the field in representation of the model.
init	`bool	None`
init_var	`bool	None`
kw_only	`bool	None`
metadata	list[Any]	The metadata list containing type-specific constraints and arbitrary objects used within Annotated metadata.
metadata_lookup	`ClassVar[dict[str, Callable[[Any], Any]	None]]`

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Constructor

Signature

def FieldInfo(
    **kwargs: Unpack[_FieldInfoInputs]
) - > null

Parameters

Name	Type	Description
**kwargs	Unpack[_FieldInfoInputs]	Keyword arguments containing field configuration such as annotation, default, alias, title, description, and metadata constraints.

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Methods

---

from_field()

@classmethod
def from_field(
    default: Any = PydanticUndefined,
    **kwargs: Unpack[_FromFieldInfoInputs]
) - > [FieldInfo](../v1/fields/fieldinfo.md?sid=pydantic_v1_fields_fieldinfo)

Create a new FieldInfo object with the Field function.

Parameters

Name	Type	Description
default	Any = PydanticUndefined	The default value for the field. Defaults to Undefined.
**kwargs	Unpack[_FromFieldInfoInputs]	Additional arguments dictionary.

Returns

Type	Description
[FieldInfo](../v1/fields/fieldinfo.md?sid=pydantic_v1_fields_fieldinfo)	A new FieldInfo object with the given parameters.

---

from_annotation()

@classmethod
def from_annotation(
    annotation: type[Any],
    _source: AnnotationSource
) - > [FieldInfo](../v1/fields/fieldinfo.md?sid=pydantic_v1_fields_fieldinfo)

Creates a FieldInfo instance from a bare annotation.

Parameters

Name	Type	Description
annotation	type[Any]	An annotation object.
_source	AnnotationSource	The source of the annotation used for internal tracking.

Returns

Type	Description
[FieldInfo](../v1/fields/fieldinfo.md?sid=pydantic_v1_fields_fieldinfo)	An instance of the field metadata.

---

from_annotated_attribute()

@classmethod
def from_annotated_attribute(
    annotation: type[Any],
    default: Any,
    _source: AnnotationSource
) - > [FieldInfo](../v1/fields/fieldinfo.md?sid=pydantic_v1_fields_fieldinfo)

Create FieldInfo from an annotation with a default value.

Parameters

Name	Type	Description
annotation	type[Any]	The type annotation of the field.
default	Any	The default value of the field.
_source	AnnotationSource	The source of the annotation used for internal tracking.

Returns

Type	Description
[FieldInfo](../v1/fields/fieldinfo.md?sid=pydantic_v1_fields_fieldinfo)	A field object with the passed values.

---

merge_field_infos()

@classmethod
def merge_field_infos(
    *field_infos: [FieldInfo](../v1/fields/fieldinfo.md?sid=pydantic_v1_fields_fieldinfo),
    **overrides: Any
) - > [FieldInfo](../v1/fields/fieldinfo.md?sid=pydantic_v1_fields_fieldinfo)

Merge FieldInfo instances keeping only explicitly set attributes.

Parameters

Name	Type	Description
*field_infos	[FieldInfo](../v1/fields/fieldinfo.md?sid=pydantic_v1_fields_fieldinfo)	The FieldInfo instances to be merged.
**overrides	Any	Attribute overrides to apply to the final merged instance.

Returns

Type	Description
[FieldInfo](../v1/fields/fieldinfo.md?sid=pydantic_v1_fields_fieldinfo)	A merged FieldInfo instance.

---

deprecation_message()

@classmethod
def deprecation_message() - > str | None

The deprecation message to be emitted, or None if not set.

Returns

Type	Description
`str	None`

---

default_factory_takes_validated_data()

@classmethod
def default_factory_takes_validated_data() - > bool | None

Whether the provided default factory callable has a validated data parameter.

Returns

Type	Description
`bool	None`

---

get_default()

@classmethod
def get_default(
    call_default_factory: bool = False,
    validated_data: dict[str, Any]| None = None
) - > Any

Get the default value.

Parameters

Name	Type	Description
call_default_factory	bool = False	Whether to call the default factory or not.
validated_data	`dict[str, Any]	None` = None

Returns

Type	Description
Any	The default value, calling the default factory if requested or PydanticUndefined if not set.

---

is_required()

@classmethod
def is_required() - > bool

Check if the field is required (i.e., does not have a default value or factory).

Returns

Type	Description
bool	True if the field is required, False otherwise.

---

rebuild_annotation()

@classmethod
def rebuild_annotation() - > Any

Attempts to rebuild the original annotation for use in function signatures.

Returns

Type	Description
Any	The rebuilt annotation, potentially wrapped in Annotated if metadata exists.

---

apply_typevars_map()

@classmethod
def apply_typevars_map(
    typevars_map: Mapping[TypeVar, Any]| None,
    globalns: GlobalsNamespace | None,
    localns: MappingNamespace | None
) - > None

Apply a typevars_map to the annotation.

Parameters

Name	Type	Description
typevars_map	`Mapping[TypeVar, Any]	None`
globalns	`GlobalsNamespace	None`
localns	`MappingNamespace	None`

Returns

Type	Description
None	null

---

asdict()

@classmethod
def asdict() - > _FieldInfoAsDict

Return a dictionary representation of the FieldInfo instance.

Returns

Type	Description
_FieldInfoAsDict	A dictionary containing annotation, metadata, and attribute mapping.

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