Route#afterModel()

This hook is called after this route's model has resolved. It follows identical async/promise semantics to beforeModel but is provided the route's resolved model in addition to the transition, and is therefore suited to performing logic that can only take place after the model has already resolved.

App.PostsRoute = Ember.Route.extend({
  afterModel: function(posts, transition) {
    if (posts.get('length') === 1) {
      this.transitionTo('post.show', posts.get('firstObject'));
    }
  }
});

Refer to documentation for beforeModel for a description of transition-pausing semantics when a promise is returned from this hook.