Function to create an immutable data structure and its associated marshmallow schema in one fell swoop

immutable_json.py

from collections import namedtuple

from marshmallow import Schema
from marshmallow.decorators import post_load


def class_and_schema(class_name, fields):
    """Create a class and its marshmallow schema.

    Example::
        from marshmallow.fields import String, Integer

        Person, PersonSchema = class_and_schema('Person', {
            'name': String (required = True),
            'age' : Integer(required = True)
        })
    """
    cls = namedtuple(name, fields.keys())

    @post_load
    def to_namedtuple(self, data):
        return cls(**data)

    schema = type(
        name + 'Schema',
        (Schema,),
        {**fields, '_to_namedtuple': to_namedtuple}
    )

    return cls, schema