Suppose you have a PostsController and a PostController. When you are looping through posts, you want them to be wrapped in a PostController.

{{#each posts itemController="post"}}
  ...
{{/each}}

You will run into problems if you want to use the same PostController for the PostRoute:

@resource 'posts'
@resource 'post', path: '/posts/:post_id'

If you go to the posts route, then to an individual post route (/posts/1) and then go back to the posts route, all your posts will be using the same instance of the PostController, which means all your posts will have the same title, id, etc. This issue is discussed on Github.

A quick workaround would be to do this: create initializers/postItemController.js.coffee:

Ember.Application.initializer
  name: 'postItemController'

  initialize: (container) ->
    App.register('controller', 'postItem', App.PostController)

And then use the PostItemController in your template:

{{#each posts itemController="postItem"}}
  ...
{{/each}}

The tip is extracted from @tchak's jsffidle, all credit goes to him!

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