Using Flask-Restful's fields, how do I have a "catchall" field?
<p>I'm using <a href="http://flask-restful-cn.readthedocs.org/en/0.3.4/" rel="nofollow">Flask-Restful</a>. I'd like to have a structured marshal, but with an arbitrary field that could contain any other valid JSON data. </p>

<p>For example, suppose that I have a resource for users with 'name' and 'birth_date', but also a 'preferences' field that contains any arbitrary JSON:</p>

<pre><code>from flask_restful import Resource, marshal_with, fields
import datetime
class MyResource(Resource):
    resource_fields = {
        'name': fields.String,
        'birth_date': fields.DateTime,
        'preferences': fields.GeneralJson
    }

    @marshal_with(resource_fields)
    def get(self):
        return {'name': 'Newbie Newborn',
                'birth_date': datetime.datetime.now(),
                'preferences': {
                    'wine': 'cab-sav',
                    'cheese': 'cheddar',
                    'favorite_movies': ['The Big Lebowski', 'Anchorman']}
                }
</code></pre>

<p>The problem with this, of course, is that <code>fields.GeneralJson</code> does not exist. What should I do to define a "schema-less" section of a JSON schema using Flask-Restful?</p>