Minimal Marshmallow Demo

demo.py

from marshmallow import Schema, fields
import json


class Database(Schema):
    class Meta:
        ordered = True

    name = fields.String()
    host = fields.String(attribute="conn_host")
    port = fields.Integer(attribute="conn_port")
    default_schema = fields.Function(lambda obj: obj.default_schema.name)


if __name__ == '__main__':
    class Mock(object):
        pass

    obj = Mock()
    default_schema = Mock()
    default_schema.name = "my_example"
    data = {"name": "test",
            "conn_host": "example.com",
            "conn_port": 80,
            "default_schema": default_schema
            }
    obj.__dict__.update(data)
    db_schema = Database()
    print(json.dumps(db_schema.dump(obj).data))

    db_schema_basic = Database(only=("name", "host", "port"))
    print(db_schema_basic.dumps(obj).data)

output:

{"name": "test", "host": "example.com", "port": 80, "default_schema": "my_example"}
{"name": "test", "host": "example.com", "port": 80}