Backbone + Firebase Collection

Backbone + Firebase Collection

我正在构建一个小应用程序,但无法弄清楚为什么在尝试添加到 collection 时出现错误。这是代码:

var PollCollection = Backbone.Firebase.Collection.extend({
        model: Poll,
        url: 'https://***.firebaseio.com/polls',
   });

   var Poll = Backbone.Model.extend({
        defaults: {
            title: 'title',
        }
   });

var pollCollection = new PollCollection();
pollCollection.create({title: "test"});

有什么想法吗?谢谢!

如果我将模型移到集合上方,一切正常