Question

What should be an EmberJS pre 4 controller be called for the template in a subdirectory say sample/header.hbs I cannot name the controller HeaderController ?

Answer 1

What should be an EmberJS pre 4 controller be called for the template in a subdirectory say sample/header.hbs

The convention would be to have controller named SampleHeaderController.

I cannot name the controller HeaderController ?

Sure you can, but additional configuration will be required if you decide to use unconventional names. If you want to use a different controller than the route handler’s controller, pass the controller option when rendering the route:

App.SampleHeaderRoute = Ember.Route.extend({
  renderTemplate: function() {
    this.render({ controller: 'header' });
  }
});

See http://emberjs.com/guides/routing/rendering-a-template/ for more detail.