Retrieve data from multiple models

I've got a blog-post-editor.

The blog-post I'm editing is the model. Now I'd need all categories for the blog-post stored in a select-box.

What's the best way to retrieve and display those categories?

Currently I'd do it like this in the controller but they are about to be deprecated in Ember 2.0:

categories: function() {
  return this.get('store').find('category');
}.property()