Demo from Tweet - 2020-10-30

components.data-provider\.js

import Component from '@glimmer/component';
import { setComponentTemplate } from '@ember/component';
import { hbs } from 'ember-cli-htmlbars';

export default setComponentTemplate(
  hbs`
    {{yield this.existingData this.emptyData}}
  `,
  class DataProvider extends Component {
    get emptyData() {}

    get existingData() {
      return { 
        data: { 
          allBooks: { 
            Books: [
              { title: 'Hello'}, 
              { title: 'There'}
            ]
          }
        }
      }
    }
  }
);

templates.application\.hbs

<h1>Demo of <a href="https://twitter.com/nullvoxpopuli/status/1322324108600840193">this tweet</a></h1>
<br>
<br>

<DataProvider as |queryStateExists queryStateEmpty|>
  Data exists: <br>
  
  <SnippetFromTheTweet @queryState={{queryStateExists}} />
  
  <br>
  
  Data does not exist: <br>
  
  <SnippetFromTheTweet @queryState={{queryStateEmpty}} />
  
</DataProvider>

twiddle\.json

{
  "version": "0.17.1",
  "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"
  }
}