core-mixins

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle'
});

mixins.routes.core-foo.js

export default Ember.Mixin.create({
  updateModel() {
    return (this._super() || '') + '1';
  }
});

mixins.routes.foo.js

import CoreFooMixin from 'app/mixins/routes/core-foo';

export default Ember.Mixin.create(CoreFooMixin, {
  updateModel() {
    return (this._super() || '') + '3';
  }
	
});

router.js

import EmberRouter from '@ember/routing/router';
import config from './config/environment';

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

Router.map(function() {
  this.route('foo', {path: '/'});
});

export default Router;

routes.core-foo.js

import Ember from 'ember';
import CoreFooMixin from 'app/mixins/routes/core-foo';

export default Ember.Route.extend(CoreFooMixin, {
  updateModel() {
    return (this._super() || '') + '2';
  }
});

routes.foo.js

import CoreFooRoute from 'app/routes/core-foo';
import FooMixin from 'app/mixins/routes/foo';

export default CoreFooRoute.extend(FooMixin, {
  updateModel() {
    return (this._super() || '') + '4';
  },
  
  model() {
    return this.updateModel();
  }
});

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<br>
<br>
{{outlet}}
<br>
<br>

templates.foo.hbs

Foo page!

{{model}}

twiddle.json

{
  "version": "0.15.0",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.js",
    "ember": "3.2.2",
    "ember-template-compiler": "3.2.2",
    "ember-testing": "3.2.2"
  },
  "addons": {
    "ember-data": "3.2.0"
  }
}