Loading Children

controllers.application\.js

import Controller from '@ember/controller';

export default class ApplicationController extends Controller {
  appName = 'Ember Twiddle';
}

mirage.config\.js

export default function() {
  this.get('/parents');
  this.get('/parents/:id', { timing: 2000 });
}

mirage.scenarios.default\.js

export default function(server) {
	server.create('parent', { 
    name: 'parent 1',
    children: [
    	server.create('child', { name: 'child 1' }),
  		server.create('child', { name: 'child 2' }),
  		server.create('child', { name: 'child 3' })
    ]
  });
}

models.child\.js

import Model, { attr, hasMany } from '@ember-data/model';

export default class extends Model {
  @attr('string') name;
}

models.parent\.js

import Model, { attr, hasMany } from '@ember-data/model';

export default class extends Model {
  @attr('string') name;
  @hasMany('child') children;
  
  get childrenLoading() {
    return this.hasMany('children').load().isPending;
  }
}

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('second-route', { path: '/second-route/:parent_id' });

});

export default Router;

routes.application\.js

import Route from '@ember/routing/route';

export default Route.extend({
  model() {
    return this.store.findAll('parent');
  }
});

routes.second-route\.js

import Route from '@ember/routing/route';

export default Route.extend({
  model(params) {
    return this.store.findRecord('parent', params.parent_id, { 
      include: 'children'
    });
  }
});

templates.application\.hbs

<h1>App route</h1>
{{#each this.model as |parent|}}
  <div>{{parent.name}}</div>
  <LinkTo @route="second-route" @model={{parent.id}}>
    Go to second route with this model
  </LinkTo>
{{/each}}

{{outlet}}

templates.second-route\.hbs

<h1>Second route</h1>

<div>model.isLoading: {{this.model.isLoading}}</div>
<div>model.isLoaded: {{this.model.isLoaded}}</div>
<div>model.isReloading: {{this.model.isReloading}}</div>
<br>
<br>
<div>model.children.isPending: {{this.model.children.isPending}}</div>
<div>model.children.isSettled: {{this.model.children.isSettled}}</div>
<br>
<br>
<div>model.childrenLoading: {{this.model.childrenLoading}}</div>
<br>
<br>

<div>
  Parent name: {{this.model.name}}
</div>
{{#each this.model.children as |child|}}
  <div>{{child.name}}</div>
{{else}}
  {{#if this.model.childrenLoading}}
    <div>Loading...</div>
  {{else}}
  	<div>Nothing to display</div>
  {{/if}}
{{/each}}

twiddle\.json

{
  "version": "0.17.1",
  "ENV": {
  	"ember-cli-mirage": {
    	"enabled": true
    }
  },
  "EmberENV": {
    "FEATURES": {},
    "_TEMPLATE_ONLY_GLIMMER_COMPONENTS": false,
    "_APPLICATION_TEMPLATE_WRAPPER": true,
    "_JQUERY_INTEGRATION": true
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/3.5.1/jquery.js",
    "ember": "3.18.1",
    "ember-template-compiler": "3.18.1",
    "ember-testing": "3.18.1"
  },
  "addons": {
    "@glimmer/component": "1.0.0",
    "ember-data": "3.18.0",
    "ember-cli-mirage": "1.1.8"
  }
}