Get ForiengKey Fields for serialization

    def get_modelfield(instance, field):
        field_path = field.split('__')
        if len(field_path) > 1:
            attr = field_path[-1]
            for fattr in field_path:
                if attr == fattr:
                    return getattr(instance, attr)
                instance = getattr(instance, fattr)
        return getattr(instance, field)