Custom error handling

By default, Schema.load will raise a ValidationError if passed invalid data.

You can specify a custom error-handling function for a Schema by overriding the handle_error method. The method receives the ValidationError and the original input data to be deserialized.

import logging
from marshmallow import Schema, fields


class AppError(Exception):
    pass


class UserSchema(Schema):
    email = fields.Email()

    def handle_error(self, exc, data, **kwargs):
        """Log and raise our custom exception when (de)serialization fails."""
        logging.error(exc.messages)
        raise AppError("An error occurred with input: {0}".format(data))


schema = UserSchema()
schema.load({"email": "invalid-email"})  # raises AppError