Example of manual relationship tracking with "virtual" vars to allow for rollback of relationships in ember data

photographer.coffee

PhotographerEditRoute = Ember.Route.extend

  model: ->
    @session.get('user').then (user) ->
      user.get('photographer')

  setupController: (controller, model) ->
    @_super controller, model
    controller.set 'availableCategories', @store.find('category')
    @resetSelectedCategories()

  actions:
    save: ->
      @setModelCategoriesToSelected()
      @get('controller.model').save().then (photographer) =>
        @resetSelectedCategories()

  resetSelectedCategories: ->
    @set 'controller.selectedCategories', Ember.A()
    @get('controller.model.categories').forEach (category) =>
      @get('controller.selectedCategories').pushObject category

  setModelCategoriesToSelected: ->
    categories = @get 'controller.model.categories'
    selectedCategories = @get 'controller.selectedCategories'

    list = categories.toArray()
    list.forEach (category) ->
      categories.removeObject category
    categories.pushObjects selectedCategories