Parent route query params

controllers.application.js

import Ember from 'ember';

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

controllers.series.js

import Ember from 'ember';

export default Ember.Controller.extend({
  queryParams: ['category']
});

helpers.pretty-print.js

import Ember from 'ember';

export function prettyPrint(params/*, hash*/) {
  return JSON.stringify(params[0], 0, 2);
}

export default Ember.Helper.helper(prettyPrint);

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('series', { path: '/:series_slug' }, function() {
    this.route('video', { path: '/:video_slug' });
  });
});

export default Router;

routes.series.video.js

import Ember from 'ember';

export default Ember.Route.extend({
  model() {
    return this.paramsFor('series');
  }
});

templates.application.hbs

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

templates.series.video.hbs

<p>I'm the video route, these are my params:</p>
<p>{{pretty-print model}}</p>

twiddle.json

{
  "version": "0.15.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.js",
    "ember": "3.4.3",
    "ember-template-compiler": "3.4.3",
    "ember-testing": "3.4.3"
  },
  "addons": {
    "ember-data": "3.4.2"
  }
}