def load_fixture(self, body, attachment_bodies={}):
        '''
        Loads the document into the database from json string. Fakes the
        attachments if necessary.'''
        doc = json.loads(body)
        self._documents[doc['_id']] = doc
        self._attachments[doc['_id']] = dict()
        for name in doc.get('_attachments', list()):
            attachment_body = attachment_bodies.get(name, 'stub')
            self._attachments[doc['_id']][name] = attachment_body