Question

When using Ember.StateManager, the most common transition between Em.States involve some parameter or another. Currently, I am using instance variables within the StateManager to pass parameters between States, when I do go from one state to another using goToState. This seems incredibly ugly to me. Is there a reason there is not a more standard way of passing parameters? Or should I use a different pattern.

For example,

App.stateManager = Em.StateManager.create({
  initialState: 'listContacts',
  listContacts: Em.ViewState.create({
    ...
    actionSelectContact: function(manager, context) {
      manager.set('selectedContact', context);
      manager.goToState('showContact');
    }
  }),
  showContact: Em.ViewState.create({
    enter: function(manager, transition) {
      var contactToShow = manager.get('selectedContact');
      ...
    }
    ...
  })
})

Is there a better way to do this parameter passing between states?

Answer 1

Tom Dale just added a transitionTo method to deal with this. transitionTo takes a context object along with the name of the target state. Now within your action you could do something like,

viewStates = Ember.StateManager.create({
  showingPeople: Ember.ViewState.create({
    view: ContactListView
  }),

  showDetailAction: function(mgr, selectedPerson) {
    mgr.transitionTo('showingPersonDetail', selectedPerson);
  },

  showingPersonDetail: Ember.ViewState.create({
    setupContext: function(manager, context) {
      this.set('person', context);
    },
    view: PersonDetailView
  })
})

You could also get more fancier and pass parameters for multiple states along the way like,

stateManager.transitionTo(['planters', { company: true }], ['nuts', { product: true }]);