Ember: discard changes when leaving page

ember_model_changes.js

/**
 * Rolls back changes on a model (and deletes new models) when leaving
 * the page without saving. The user will also be notified if the model
 * has changed when trying to leave the page.
*/
App.HandleModelChanges = Ember.Mixin.create({

  deactivate: function() {
    var model = this.get('controller.model');
    model.rollback();
    if (model.get('isNew')) {
      model.deleteRecord();
    }
  },

  actions: {
    willTransition: function(transition) {
      var model = this.get('controller.model');
      if (model.get('isDirty') && !confirm('Do you really want to leave the page ? All the changes will be lost.')) {
        transition.abort();
      }
    }
  },

});


App.PostRoute = Ember.Route.extend(App.HandleModelChanges);


App.PostEditController = Ember.ObjectController.extend({
  isSaving: false,

  actions: {
    cancel: function () {
      this.transitionToRoute('post');
    },

    save: function () {
      var self = this,
          post = self.get('model');

      self.set('isSaving', true);

      post.get('errors').clear();
      return post.save().then(function () {
        self.transitionToRoute('post', post);
      }).catch(function (error) {
        // ...
      }).finally(function () {
        self.set('isSaving', false);
      });
    },
  },
});