Flask SqlAlchemy engine with obfuscated string columns

databases.py

from typing import Any
from typing import Optional

import sqlalchemy.types as types
from flask_sqlalchemy import SQLAlchemy

class ObfuscatedString(types.TypeDecorator):
    """
    String column type for use with SQLAlchemy models whose
    content should not appear in logs or exceptions
    """

    impl = types.String

    class Repr(str):
        def __repr__(self) -> str:
            return "********"

    def process_bind_param(self, value: Optional[str], dialect: Any) -> Optional[Repr]:
        return self.Repr(value) if value else None

    def process_result_value(
        self, value: Optional[Repr], dialect: Any
    ) -> Optional[str]:
        return str(value) if value else None


db = SQLAlchemy()
setattr(db, "ObfuscatedString", ObfuscatedString)