Function constr

pydantic/types.py:752–834

!!! warning "Discouraged" This function is **discouraged** in favor of using [`Annotated`](https://docs.python.org/3/library/typing.html#typing.Annotated) with [`StringConstraints`][pydantic.types.StringConstraints] instead. This function will be **deprecated**

(
    *,
    strip_whitespace: bool | None = None,
    to_upper: bool | None = None,
    to_lower: bool | None = None,
    strict: bool | None = None,
    min_length: int | None = None,
    max_length: int | None = None,
    pattern: str | Pattern[str] | None = None,
    ascii_only: bool | None = None,
)

def constr(
    *,
    strip_whitespace: bool | None = None,
    to_upper: bool | None = None,
    to_lower: bool | None = None,
    strict: bool | None = None,
    min_length: int | None = None,
    max_length: int | None = None,
    pattern: str | Pattern[str] | None = None,
    ascii_only: bool | None = None,
) -> type[str]:
    """
    !!! warning "Discouraged"
        This function is **discouraged** in favor of using
        [`Annotated`](https://docs.python.org/3/library/typing.html#typing.Annotated) with
        [`StringConstraints`][pydantic.types.StringConstraints] instead.

        This function will be **deprecated** in Pydantic 3.0.

        The reason is that `constr` returns a type, which doesn't play well with static analysis tools.

        === ":x: Don't do this"
            ```python
            from pydantic import BaseModel, constr

            class Foo(BaseModel):
                bar: constr(strip_whitespace=True, to_upper=True, pattern=r'^[A-Z]+$')
            ```

        === ":white_check_mark: Do this"
            ```python
            from typing import Annotated

            from pydantic import BaseModel, StringConstraints

            class Foo(BaseModel):
                bar: Annotated[
                    str,
                    StringConstraints(
                        strip_whitespace=True, to_upper=True, pattern=r'^[A-Z]+$'
                    ),
                ]
            ```

    A wrapper around `str` that allows for additional constraints.

    ```python
    from pydantic import BaseModel, constr

    class Foo(BaseModel):
        bar: constr(strip_whitespace=True, to_upper=True)

    foo = Foo(bar='  hello  ')
    print(foo)
    #> bar='HELLO'
    ```

    Args: