Serializing a model to json with a nested class doesn't expose the nested class

Summary: The problem is that I cannot access the thumbnail image from a nested class in the serialized model and I don't know how to expose it in the JSON response.

Description: I am trying to serialize my Thing model to JSON and it works, in a fashion. I get the following in my JSON response:

// JSON response
[
    {
        pk: 1
        model: "base.thing"
        fields: {
            active: true
            created_at: "2011-04-13 07:18:05"
            num_views: 1
            file: "things/5216868239_b53b8d5e80_b.jpg"
            title: "ding ding ding"
        }
    }
]

I just started using django-imagekit to manipulate the Thing images to thumbnail sizes and it works in normal usage, i.e. running 'thing.thumbnail_image.url' in a template returns the correct url to the thumbnail image.

The sandbox code I'm playing around with:

# base/models.py
from django.db import models
from imagekit.models import ImageModel

class Thing(ImageModel):
    title = models.CharField(max_length=30)
    file = models.ImageField(upload_to='things')
    created_at = models.DateTimeField(auto_now_add=True)
    active = models.BooleanField()
    num_views = models.PositiveIntegerField(editable=False, default=0)

    def __unicode__(self):
        return self.title

    class IKOptions:
        spec_module = 'base.specs'
        image_field = 'file'
        save_count_as = 'num_views'

# base/views.py
from django.views.generic.base import View
from django.views.generic.list import MultipleObjectTemplateResponseMixin, ListView

from base.models import Thing    
from django import http
from django.utils import simplejson as json

from utils import JsonResponse

class JSONResponseMixin(object):
    def render_to_response(self, context):
        "Returns a JSON response containing 'context' as payload"
        return self.get_json_response(context)

    def get_json_response(self, content, **httpresponse_kwargs):
        "Construct an `HttpResponse` object."
        return JsonResponse(content['thing_list']) # I can't serialize the content object by itself

class ThingsView(JSONResponseMixin, ListView):
    model = Thing
    context_object_name = "thing_list"
    template_name = "base/thing_list.html"

    def render_to_response(self, context):
        if self.request.GET.get('format', 'html') == 'json':
            return JSONResponseMixin.render_to_response(self, context)
        else:
            return ListView.render_to_response(self, context)

# base/specs.py
from imagekit.specs import ImageSpec
from imagekit import processors

class ResizeThumb(processors.Resize):
    width = 100
    height = 75
    crop = True

class ResizeDisplay(processors.Resize):
    width = 600

class EnchanceThumb(processors.Adjustment):
    contrast = 1.2
    sharpness = 1.1

class Thumbnail(ImageSpec):
    access_as = 'thumbnail_image'
    pre_cache = True
    processors = [ResizeThumb, EnchanceThumb]

class Display(ImageSpec):
    increment_count = True
    processors = [ResizeDisplay]

# utils.py
from django.core.serializers import json, serialize
from django.db.models.query import QuerySet
from django.http import HttpResponse
from django.utils import simplejson

class JsonResponse(HttpResponse):
    def __init__(self, object):
        if isinstance(object, QuerySet):
            content = serialize('json', object)
        else:
            content = simplejson.dumps(
                object, indent=2, cls=json.DjangoJSONEncoder,
                ensure_ascii=False)
        super(JsonResponse, self).__init__(
            content, content_type='application/json')

I appreciate any help with this, it's been blocking me for a day.

Best regards-

Using versions:
Django 1.3
PIL 1.1.7
django-imagekit 0.3.6
simplejson 2.1.3

I couldn't figure out how to expose the inner class over JSON so I chose an alternative way of doing it and dropping django-imagekit and manually resizing the image to a thumbnail and saving it in the model's save() function.

im = ImageOps.fit(im, (sizes['thumbnail']['width'], sizes['thumbnail']['height'],), method=Image.ANTIALIAS)
thumbname = filename + "_" + str(sizes['thumbnail']['width']) + "x" + str(sizes['thumbnail']['height']) + ".jpg"
im.save(fullpath + '/' + thumbname)

It's a less than clean approach but it works for now.