Path() — fastapi Function Reference

Architecture documentation for the Path() function in param_functions.py from the fastapi codebase.

Function python FastAPI Routing called by 1

Entity Profile

FastAPI→ Routing→ Path() — fastapi Function Reference

Dependency Diagram

graph TD
  158c8915_611c_64c9_cffc_1d3d9f3987dc["Path()"]
  24a9a43e_697f_81ce_6a7c_28a423a6f93b["param_functions.py"]
  158c8915_611c_64c9_cffc_1d3d9f3987dc -->|defined in| 24a9a43e_697f_81ce_6a7c_28a423a6f93b
  8f264cc6_9c21_2715_d7f6_3cfe387c114b["test_no_annotated_defaults()"]
  8f264cc6_9c21_2715_d7f6_3cfe387c114b -->|calls| 158c8915_611c_64c9_cffc_1d3d9f3987dc
  style 158c8915_611c_64c9_cffc_1d3d9f3987dc fill:#6366f1,stroke:#818cf8,color:#fff

Relationship Graph

Source Code

fastapi/param_functions.py lines 14–355

def Path(  # noqa: N802
    default: Annotated[
        Any,
        Doc(
            """
            Default value if the parameter field is not set.

            This doesn't affect `Path` parameters as the value is always required.
            The parameter is available only for compatibility.
            """
        ),
    ] = ...,
    *,
    default_factory: Annotated[
        Union[Callable[[], Any], None],
        Doc(
            """
            A callable to generate the default value.

            This doesn't affect `Path` parameters as the value is always required.
            The parameter is available only for compatibility.
            """
        ),
    ] = _Unset,
    alias: Annotated[
        Optional[str],
        Doc(
            """
            An alternative name for the parameter field.

            This will be used to extract the data and for the generated OpenAPI.
            It is particularly useful when you can't use the name you want because it
            is a Python reserved keyword or similar.
            """
        ),
    ] = None,
    alias_priority: Annotated[
        Union[int, None],
        Doc(
            """
            Priority of the alias. This affects whether an alias generator is used.
            """
        ),
    ] = _Unset,
    validation_alias: Annotated[
        Union[str, AliasPath, AliasChoices, None],
        Doc(
            """
            'Whitelist' validation step. The parameter field will be the single one
            allowed by the alias or set of aliases defined.
            """
        ),
    ] = None,
    serialization_alias: Annotated[
        Union[str, None],
        Doc(
            """
            'Blacklist' validation step. The vanilla parameter field will be the
            single one of the alias' or set of aliases' fields and all the other
            fields will be ignored at serialization time.
            """
        ),
    ] = None,
    title: Annotated[
        Optional[str],
        Doc(
            """
            Human-readable title.

            Read more about it in the
            [FastAPI docs for Path Parameters and Numeric Validations](https://fastapi.tiangolo.com/tutorial/path-params-numeric-validations/#declare-metadata)
            """
        ),
    ] = None,
    description: Annotated[
        Optional[str],
        Doc(
            """
            Human-readable description.
            """
        ),