Paginated Collections

controllers.application\.js

import Controller from '@ember/controller';
import Paginated from '../paginated';
import { tracked } from '@glimmer/tracking';

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

  @tracked pageIndex = 0;

  data = Paginated.create();
}

paginated\.js

import ArrayProxy from '@ember/array/proxy';
import { tracked } from '@glimmer/tracking';
import { A } from '@ember/array';

const Page1 = {
  links: {},
  meta: {
    pageName: 'page 1!',
  },
  data: [
    {
      type: 'post',
      id: '1',
      attributes: {
        title: 'A spiffy title 1', 
      }
    },
        {
      type: 'post',
      id: '2',
      attributes: {
        title: 'A spiffy title 2', 
      }
    },
  ]
}
const Page2 = {
  links: {},
  meta: {
    pageName: 'page 2!',
  },
  data: [
    {
      type: 'post',
      id: '3',
      attributes: {
        title: 'A spiffy title 3', 
      }
    },
    {
      type: 'post',
      id: '4',
      attributes: {
        title: 'A spiffy title 4', 
      }
    }
  ]
}
const Page3 = {
  links: {},
  meta: {
    pageName: 'page 3!',
  },
  data: [
    {
      type: 'post',
      id: '5',
      attributes: {
        title: 'A spiffy title 5', 
      }
    },
    {
      type: 'post',
      id: '6',
      attributes: {
        title: 'A spiffy title 6', 
      }
    }
  ]
}

class Resource {
  constructor(data) {
    this.id = data.id;
    this.type = data.type;
    Object.assign(this, data.attributes);
  }
}

class Collection {
  @tracked links;
  @tracked meta;
  @tracked data;
  
  constructor({ links, meta, data }) {
    this.links = links;
    this.meta = meta;
    this.data = A(data.map(d => new Resource(d)));
  }
}

const pagesForCollection = A([
  new Collection(Page1),
  new Collection(Page2),
  new Collection(Page3),
]);

// Extending ArrayProxy is only necessary in older Ember versions
export default class PaginatedCollection extends ArrayProxy {
  @tracked pages = pagesForCollection;

	get length() {
  	return this.pages.reduce((count, page) => { return count + page.data.length; }, 0);
  }

  objectAt(index) {
      const { pages } = this;
      let counted = 0;
    
  	  for (let i = 0; i < pages.length; i++) {
        let startCount = counted;
        counted += pages[i].data.length;
        if (index < counted) {
           return pages[i].data[index - startCount];
        }
      }
      return undefined; 
  }

  forEach(cb) {
    for (let index = 0; index < this.length; index++) {
      cb(this.objectAt(index));
    }
  }
}

templates.application\.hbs

<h1>Welcome to {{this.appName}}</h1>
<br>

{{#let (get this.data.pages this.pageIndex) as |page|}}

<h3>Posts {{page.meta.pageName}}</h3>

<ul>
{{#each page.data as |post|}}
   <li>{{post.title}}</li>
{{/each}}
</ul>

{{/let}}

{{#each this.data.pages as |page index|}}
  <button {{on 'click' (fn (mut this.pageIndex) index)}}>{{index}}</button>
{{/each}}



<h3>All Posts</h3>
<ul>
  {{#each this.data as |item index|}}
    <li>{{item.title}}</li>
  {{/each}}
</ul>



<br>
{{outlet}}
<br>
<br>

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"
  }
}