Problem with custom error messages for field validation in Marshmallow-CodePudding

I'm trying to add a customized error message for a class field in Marshamallow's schema. The field representation looks like this:

phone_number = fields.String(validate=Length(max=20),
                             error_messages={'invalid': 'Phone number must be a string shorter than'
                                                        '20 letters.'})

I was expecting that after loading the request data to a schema, I would get the error "Phone number must be a string shorter than 20 letters.", however, I'm still receiving the default message "Longer than maximum length 20.". The code for loading the request data is:

        try:
            request_data = EditInvestorSchema().load(request.json)
        except ValidationError as error:
            return get_response(400, list(error.messages.values())[0])

Can anyone shed some light on what might be happening?

CodePudding user response：

If you define the message in the validator it should work. See here for the documentation of the validator.

phone_number = fields.String(
    validate=Length(
        max=20, 
        error='Phone number must be a string shorter than 20 letters.'
    )
)