Class StringConstraints

pydantic/types.py:693–749

!!! abstract "Usage Documentation" [String types](./standard_library_types.md#strings) A field metadata class to apply constraints to `str` types. Use this class as an annotation via [`Annotated`](https://docs.python.org/3/library/typing.html#typing.Annotated), as seen below. A

@_dataclasses.dataclass(frozen=True)
class StringConstraints(annotated_types.GroupedMetadata):
    """!!! abstract "Usage Documentation"
        [String types](./standard_library_types.md#strings)

    A field metadata class to apply constraints to `str` types.
    Use this class as an annotation via [`Annotated`](https://docs.python.org/3/library/typing.html#typing.Annotated), as seen below.

    Attributes:
        strip_whitespace: Whether to remove leading and trailing whitespace.
        to_upper: Whether to convert the string to uppercase.
        to_lower: Whether to convert the string to lowercase.
        strict: Whether to validate the string in strict mode.
        min_length: The minimum length of the string.
        max_length: The maximum length of the string.
        pattern: A regex pattern that the string must match.
        ascii_only: Whether the string should contain only ASCII characters.

    Example:
        ```python
        from typing import Annotated

        from pydantic.types import StringConstraints

        ConstrainedStr = Annotated[str, StringConstraints(min_length=1, max_length=10)]
        ```
    """

    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 __iter__(self) -> Iterator[BaseMetadata]:
        if self.min_length is not None:
            yield MinLen(self.min_length)
        if self.max_length is not None:
            yield MaxLen(self.max_length)
        if self.strict is not None:
            yield Strict(self.strict)
        if (
            self.strip_whitespace is not None
            or self.pattern is not None
            or self.to_lower is not None
            or self.to_upper is not None
            or self.ascii_only is not None
        ):
            yield _fields.pydantic_general_metadata(
                strip_whitespace=self.strip_whitespace,
                to_upper=self.to_upper,
                to_lower=self.to_lower,
                pattern=self.pattern,
                ascii_only=self.ascii_only,
            )