Upon receiving this event, the controller knows that the feed data is cached in the model object and can be presented in the view.
一旦收到此事件，控制器就会知道提要数据是在模型对象中缓存并可在视图中展示。
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Be sure that this id doesn't change over time by inadvertently passing in variables from the controller - in the case of the feed id, you want it to be both unique and invariant.