New Twiddle

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  
  myService: Ember.inject.service()
  
});

router.js

import Ember from 'ember';
import config from './config/environment';

const Router = Ember.Router.extend({
  location: 'none',
  rootURL: config.rootURL
});

Router.map(function() {
  this.route('foo');
  this.route('bar');
});

export default Router;

routes.bar.js

import Ember from 'ember';

export default Ember.Route.extend({
  
  myService: Ember.inject.service(),
  
  beforeModel (trans) {
    const svc = this.get('myService');
    svc.add('in bar::beforeModel');
    const oldTrans = this.get('myService.trans');
    if (oldTrans) {
      svc.add('have oldTrans, retrying transition');
      trans.retry(); 
    }
  }
  
});

routes.foo.js

import Ember from 'ember';

export default Ember.Route.extend({
  
  myService: Ember.inject.service(),
  
  beforeModel (trans) {
    const svc = this.get('myService');
    const doIt = svc.get('state');
    svc.add('in foo::beforeModel');
    if (doIt) {
      svc.add('in doIt is true, transitioning to bar');
     	svc.set('trans', trans);
    	svc.set('doIt', false);
      transition.abort();
      this.transitionTo('bar');
    }
  }
  
});

services.my-service.js

import Ember from 'ember';

export default Ember.Service.extend({
  doIt: false,
  
  log: [],
  
  add (log) {
   this.get('log').pushObject(log); 
  }
});

styles.app.css

body {
  margin: 12px 16px;
  font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif;
  font-size: 12pt;
}

li {
 background-color: gray;
  border: solid 1px black;
  padding: 5px
}

li a {
 text-decoration: none; 
}

li.active {
 background-color: lightgray 
}

li.active a {
 color: green; 
}

templates.application.hbs

<h3>State: {{myService.doIt}}</h3>

<ul>
{{#active-link}}
  {{link-to "Index" "index"}}
{{/active-link}}
{{#active-link}}
  {{link-to "Foo" "foo"}}
{{/active-link}}
{{#active-link}}
  {{link-to "Bar" "bar"}}
{{/active-link}}
</ul>

{{#each myService.log as |logentry|}}
	<div>{{logentry}}</div>
{{/each}}

twiddle.json

{
  "version": "0.10.7",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.10.0",
    "ember-data": "2.10.0",
    "ember-template-compiler": "2.10.0",
    "ember-testing": "2.10.0"
  },
  "addons": {
    "ember-cli-active-link-wrapper": "0.3.2"
  }
}