Question

I am learning emberjs form trek.github.com. That tutorial used both Em.ObjectController and Em.ArrayController. And There is also Em.Controller.

I am confused when to use them, I guess Em.ObjectController is for single object, Em.ArrayController is for array and Em.Controller is just for ApplicationController.

Is there any blessed rule for when to use which?

Answer 1

Usually, if your Controller represent a list of items, you would use the Ember.ArrayController, and if the controller represents a single item, you would use the Ember.ObjectController. Something like the following:

MyApp.ContactsController = Ember.ArrayController.extend({
    content: [],
    selectedContact: null
});

MyApp.SelectedContactController = Ember.ObjectController.extend({
    contentBinding: 'contactsController.selectedContact',
    contactsController: null
});

Then in your Ember.Router (if you use them), you would connect the two inside the connectOutlets function:

connectOutlets: function(router) {
    router.get('selectedContactController').connectControllers('contacts');
}

Edit: I have never used the Ember.Controller. Looking at the source code, it seems like you might want to use this if you are building a custom controller that doesn’t fit in with the two other controllers.