Custom Regex Errors

class RegexValidator

Bases: object

Base class for creating reusable Pydantic regex validators.

Usage Example

To create a new validator, subclass RegexValidator:

import re

class PasswordValidator(
    RegexValidator,
    pattern=re.compile(r"^(?=.*[A-Z]).{8,}$"),
    error_message="Password must be at least 8 chars with 1 uppercase"
):
    """Validator for user passwords."""

pattern: ClassVar[Pattern[str]]

error_message: ClassVar[str]

classmethod __init_subclass__(pattern: Pattern[str], error_message: str) → None

Configure the validator subclass with a specific regex pattern.

Parameters:

• pattern (Pattern[str]) – The compiled regular expression to validate against.

• error_message (str) – The custom message returned when validation fails.

classmethod __get_pydantic_core_schema__(source: type[Any], handler: GetCoreSchemaHandler) → CoreSchema

Generate the Pydantic Core Schema for the validator.

Integrates the custom regex check into the standard validation chain.