Param

This class serves as a base for defining request parameters, extending metadata capabilities for data validation and OpenAPI schema generation. It supports a wide range of constraints such as numeric limits, string patterns, and metadata like titles, descriptions, and examples. By inheriting from field information structures, it integrates seamlessly with validation and serialization workflows.

Attributes

Attribute	Type	Description
in_	[ParamTypes](paramtypes.md?sid=fastapi_params_paramtypes)	The location of the parameter in the HTTP request, defined by the ParamTypes enum.

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Constructor

Signature

def Param(
    default: Any = Undefined,
    default_factory: Callable[[], Any]| None = _Unset,
    annotation: Any | None = None,
    alias: str | None = None,
    alias_priority: int | None = _Unset,
    validation_alias: str | AliasPath | AliasChoices | None = None,
    serialization_alias: str | None = None,
    title: str | None = None,
    description: str | None = None,
    gt: float | None = None,
    ge: float | None = None,
    lt: float | None = None,
    le: float | None = None,
    min_length: int | None = None,
    max_length: int | None = None,
    pattern: str | None = None,
    regex: str | None = None,
    discriminator: str | None = None,
    strict: bool | None = _Unset,
    multiple_of: float | None = _Unset,
    allow_inf_nan: bool | None = _Unset,
    max_digits: int | None = _Unset,
    decimal_places: int | None = _Unset,
    examples: list[Any]| None = None,
    example: Any | None = _Unset,
    openapi_examples: dict[str, [Example](../openapi/models/example.md?sid=fastapi_openapi_models_example)]| None = None,
    deprecated: deprecated | str | bool | None = None,
    include_in_schema: bool = True,
    json_schema_extra: dict[str, Any]| None = None,
    extra: Any
) - > null

Parameters

Name	Type	Description
default	Any = Undefined	The default value for the parameter.
default_factory	`Callable[[], Any]	None` = _Unset
annotation	`Any	None` = None
alias	`str	None` = None
alias_priority	`int	None` = _Unset
validation_alias	`str	AliasPath
serialization_alias	`str	None` = None
title	`str	None` = None
description	`str	None` = None
gt	`float	None` = None
ge	`float	None` = None
lt	`float	None` = None
le	`float	None` = None
min_length	`int	None` = None
max_length	`int	None` = None
pattern	`str	None` = None
regex	`str	None` = None
discriminator	`str	None` = None
strict	`bool	None` = _Unset
multiple_of	`float	None` = _Unset
allow_inf_nan	`bool	None` = _Unset
max_digits	`int	None` = _Unset
decimal_places	`int	None` = _Unset
examples	`list[Any]	None` = None
example	`Any	None` = _Unset
openapi_examples	`dict[str, Example]	None` = None
deprecated	`deprecated	str
include_in_schema	bool = True	Whether to include this parameter in the generated JSON schema.
json_schema_extra	`dict[str, Any]	None` = None
extra	Any	Additional keyword arguments.

---

Signature

def Param(
    default: Any = Undefined,
    default_factory: Callable[[], Any]| None = _Unset,
    annotation: Any | None = None,
    alias: str | None = None,
    alias_priority: int | None = _Unset,
    validation_alias: str | AliasPath | AliasChoices | None = None,
    serialization_alias: str | None = None,
    title: str | None = None,
    description: str | None = None,
    gt: float | None = None,
    ge: float | None = None,
    lt: float | None = None,
    le: float | None = None,
    min_length: int | None = None,
    max_length: int | None = None,
    pattern: str | None = None,
    regex: str | None = None,
    discriminator: str | None = None,
    strict: bool | None = _Unset,
    multiple_of: float | None = _Unset,
    allow_inf_nan: bool | None = _Unset,
    max_digits: int | None = _Unset,
    decimal_places: int | None = _Unset,
    examples: list[Any]| None = None,
    example: Any | None = _Unset,
    openapi_examples: dict[str, [Example](../openapi/models/example.md?sid=fastapi_openapi_models_example)]| None = None,
    deprecated: deprecated | str | bool | None = None,
    include_in_schema: bool = True,
    json_schema_extra: dict[str, Any]| None = None,
    extra: Any
) - > null

Parameters

Name	Type	Description
default	Any = Undefined	The fixed default value to use if the parameter is not provided in the request.
default_factory	`Callable[[], Any]	None` = _Unset
annotation	`Any	None` = None
alias	`str	None` = None
alias_priority	`int	None` = _Unset
validation_alias	`str	AliasPath
serialization_alias	`str	None` = None
title	`str	None` = None
description	`str	None` = None
gt	`float	None` = None
ge	`float	None` = None
lt	`float	None` = None
le	`float	None` = None
min_length	`int	None` = None
max_length	`int	None` = None
pattern	`str	None` = None
regex	`str	None` = None
discriminator	`str	None` = None
strict	`bool	None` = _Unset
multiple_of	`float	None` = _Unset
allow_inf_nan	`bool	None` = _Unset
max_digits	`int	None` = _Unset
decimal_places	`int	None` = _Unset
examples	`list[Any]	None` = None
example	`Any	None` = _Unset
openapi_examples	`dict[str, Example]	None` = None
deprecated	`deprecated	str
include_in_schema	bool = True	Whether this parameter should be visible in the generated OpenAPI/JSON schema.
json_schema_extra	`dict[str, Any]	None` = None
extra	Any	Arbitrary keyword arguments for additional metadata or custom configuration.

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