Как преобразовать строковые данные в объект JSON в Python?

Вот образец строка, которую я получаю от одной из веб-служб,

body=%7B%22type%22%3A%22change%22%2C%22url%22%3A%22http%3A%2F%2Fapi.pachube.com%2Fv2%2Ftriggers%2F4100%22%2C%22environment%22%3A%7B%22feed%22%3A%22http%3A%2F%2Fapi.pachube.com%2Fv2%2Ffeeds%2F36133%22%2C%22title%22%3A%22Current+Cost+Bridge%22%2C%22description%22%3Anull%2C%22id%22%3A36133%7D%2C%22threshold_value%22%3Anull%2C%22timestamp%22%3A%222012-01-05T09%3A27%3A01Z%22%2C%22triggering_datastream%22%3A%7B%22url%22%3A%22http%3A%2F%2Fapi.pachube.com%2Fv2%2Ffeeds%2F36133%2Fdatastreams%2F1%22%2C%22value%22%3A%7B%22value%22%3A%22523%22%2C%22max_value%22%3A1269.0%2C%22min_value%22%3A0.0%7D%2C%22id%22%3A%221%22%2C%22units%22%3A%7B%22symbol%22%3A%22W%22%2C%22type%22%3A%22derivedUnits%22%2C%22label%22%3A%22watts%22%7D%7D%2C%22id%22%3A4100%7D

Вот код,

class Feeds():
    def GET(self):
        print "Get request is accepted."
        return render.index(None)

    def POST(self):
        print "Post request is accepted."
        print (web.data())

Теперь, когда эта веб-служба публикует указанные выше данные, как я могу преобразовать их в читаемый формат? Затем мне нужно преобразовать его в объект JSON и использовать дальше. Итак, как мне его преобразовать?

Когда я пробую этот код,

        json_data = json.loads(web.data())
        print json_data['body']
        return render.index(json_data['body'])

Выдает ошибку,

enter code Traceback (most recent call last):
File "/usr/local/lib/python2.6/dist-packages/web/application.py", line 237, in process
return self.handle()
File "/usr/local/lib/python2.6/dist-packages/web/application.py", line 228, in handle
return self._delegate(fn, self.fvars, args)
File "/usr/local/lib/python2.6/dist-packages/web/application.py", line 409, in _delegate
return handle_class(cls)
File "/usr/local/lib/python2.6/dist-packages/web/application.py", line 385, in      handle_class
return tocall(*args)
File "/home/ubuntu/pachubeConsumer/src/controllers/feeds.py", line 17, in POST
json_data = json.loads(web.data())
File "/usr/lib/python2.6/json/__init__.py", line 307, in loads
return _default_decoder.decode(s)
File "/usr/lib/python2.6/json/decoder.py", line 319, in decode
obj, end = self.raw_decode(s, idx=_w(s, 0).end())
File "/usr/lib/python2.6/json/decoder.py", line 338, in raw_decode
raise ValueError("No JSON object could be decoded")
ValueError: No JSON object could be decoded here

Где я ошибаюсь ??

Заранее спасибо.