application.hbs

<nav class="main">
  {{#linkTo "index"}}Main Page{{/linkTo}}
  {{#linkTo "shifts"}}My shifts{{/linkTo}}
  {{#linkTo "about"}}About{{/linkTo}}
  -
  {{#linkTo "login"}}Login{{/linkTo}}
</nav>

{{#if currentUser.isSignedIn}}
  <p>Logged user: {{currentUser.username}}</p>
{{else}}
  <p>Hello anonymous</p>
{{/if}}

<hr/>

{{outlet}}

currentUser.js.coffee

Syncin.initializer
  name: 'currentUser'

  initialize: (container) ->
    store = container.lookup('store:main')
    attributes = $('meta[name="current-user"]').attr('content')

    if attributes
      object = store.load(Syncin.User, JSON.parse(attributes))
      user = Syncin.User.find(object.id)

      controller = container.lookup('controller:currentUser').set('content', user)

      container.typeInjection('controller', 'currentUser', 'controller:currentUser')

login_controller.js

Syncin.LoginController = Ember.Controller.extend({

  logout: function() {
    // TODO use http DELETE
    Ember.$.post('/api/v1/sessions/logout', {}).then(function(response){
      alert("You've been signed out.");
    });
  },

  login: function() {
    var data = {
      username: this.get('username'),
      password: this.get('password')
    }
    var self = this;

    self.set('errorMessage', null);

    Ember.$.post('/api/v1/sessions', data).then(function(response){
      if (response.success) {
        alert("success. token=" + response.token);



        // Here's the problem. It works, but variables of signed user in application template are not refreshed

        user = Syncin.User.find(1); // TODO the ID you should get from response
        
        container = Syncin.__container__; // usage of internal API, that's bad
        controller = container.lookup('controller:currentUser').set('content', user);
        container.typeInjection('controller', 'currentUser', 'controller:currentUser');



        self.transitionToRoute("shifts");
      }
      else {
        self.set('errorMessage', response.message)
      }
    })
  },

  reset: function() {
    this.set("username", "");
    this.set("password", "");
    this.set("errorMessage", "");
  }
});