Django graphene mutation input validation

import graphene

class ScratchpadMutation(graphene.relay.ClientIDMutation):
    class Input:
        created_by = graphene.String(required=True)
        foobar = graphene.String()

    test = graphene.String()
    test2 = graphene.String()

    @classmethod
    def validate_created_by(cls, value: str) -> str:
        if "foo" in value:
            raise ValueError("No foo's allowed")
        return value.strip().upper()

    @classmethod
    def validate_combinations(cls, input: dict) -> dict:
        if input.get("created_by") == "TEST" and input.get("foobar") == "TEST":
            raise ValueError("Cannot have both created_by and foobar as TEST")

        return input

    @classmethod
    def validate_inputs(cls, input: dict) -> dict:
        validated_inputs = input.copy()
        for key, value in input.items():
            validation_method = f"validate_{key}"
            # Check if the method exists and run if so
            if hasattr(cls, validation_method):
                method = getattr(cls, validation_method)
                validated_inputs[key] = method(value)

        # Run other validations on all the inputs after the pre-validate/cleaning
        validated_inputs = cls.validate_combinations(validated_inputs)

        return validated_inputs

    @classmethod
    def mutate_and_get_payload(cls, root, info, **input):
        # Need to update since not all fields may have a validation method
        input = cls.validate_inputs(input)
        
        # do somthing with the inputs here
        
        return ScratchpadMutation(
            test=input.get("created_by"), test2=input.get("foobar")
        )