Ember Dynamic Routing

Prerequisites

ga-wdi-boston.ember-routing-dynamic

Objectives

By the end of this, developers should be able to:

Set up resource routes.
Create a Route object.
Configure a Route to parse information from a URL.

Preparation

Fork and clone this repository.
Install dependencies with npm install and bower install.

Code-Along: Routing to Resources

In the previous lesson on Ember routing, you learned how to generate templates and connect to them via the Router.

Routes linking to (basically) static HTML are well and good, but most of the time we're interested in showing and manipulating data from resources (e.g. products). Although the routes for resources used to be distinct from normal routes, in Ember 2 that distinction has disappeared - now, a route for a resource (such as products) looks like any other route.

// app/router.js

Router.map(function() {
  this.route('products');

  this.route('about');
  this.route('contact');
  this.route('team', function(){
    this.route('leadership');
    this.route('engineering');
    this.route('sales');
  });
});

However, in order for such a route to actually have data to load, we need to create a Route object. As you may recall from the Ember Overview lesson, the purposes of the Route object are (1) to parse the URL for a given route, and (2) to use information from that URL to load model data.

Generating this Route object is fairly easy. In the case of a products route, we can do this by running the command ember g route products; this will create two new files in the app/products directory, a Route file and a Template file.

Let's take a closer look at that Route file.

// app/products/route.js

import Ember from 'ember';

export default Ember.Route.extend({
});

The way in which a Route file makes data available to a Controller, View, or Template is through a method that we define called model - this method returns some data object that gets used within the route. In this case, let us suppose that the model method returns an array of JavaScript objects, like so:

// app/products/route.js

import Ember from 'ember';

export default Ember.Route.extend({
  model: function(){
    return [
      {
        id: 1,
        name: 'Crock Pot',
        manufacturer: 'Farberware',
        price: 40
      },
      {
        id: 2,
        name: 'Food Processor',
        manufacturer: 'Cuisinart',
        price: 25
      },
      {
        id: 3,
        name: 'Electric Griddle',
        manufacturer: 'George Foreman Grills',
        price: 15
      },
    ];
  }
});

If we wanted to access this data from a Template, we can do so by referencing a property called model from within the Template, which points back to the result of the model function from the Route. Let's make a change to the products Template so that it shows the names of the products listed above.

<!-- app/products/template.hbs -->

<!-- {{outlet}} -->
<h2> Product Listings </h2>
<ul>
{{#each model as |product|}}
  <li>{{product.name}}</li>
{{/each}}
</ul>

{{#each set as |item|}} is a new construction for Ember 2. The pipes (|) play the same role here that they do in Ruby.

Lab: Routing to Resources

Create routes for each of the teams in our app: leadership, engineering, and sales. Each route should have a model hook that loads an example collection of employees on the team. Modify the appropriate templates to render the data from each model.

Routing with Dynamic Segments

Often, we don't just want to see the full list of a particular type of resource; we want to be able to zoom in on one in particular. Although it deals with the same type of resource, because it creates a different 'view state' than looking at the list as a whole, this must be represented with a separate route. Let's call this new route product, since it concerns zooming in on one product in particular from the list.

// app/router.js

Router.map(function() {
  this.route('products');
  this.route('product', {path: '/products/:product_id'})
  this.route('about');
  this.route('contact');
  this.route('team', function(){
    this.route('leadership');
    this.route('engineering');
    this.route('sales');
  });
});

The object passed in as the second argument to the product route contains the actual path used to reach the product route. It's usually not necessary to specify the actual path, since the URL and the name of the route are usually the same; however, in this case, they are not the same, so we must specify the path explicitly.

The :product_id section of the path is called a dynamic segment; much like you've seen in Rails and Express, this part of the URL is a placeholder for a value, typically a number. The name :product_id is not special, and in fact we could have chosen any name for that segment.

As mentioned earlier, one of the two big responsibilities of the Route is to parse the URL and extract meaningful information - dynamic segments are the primary instance of this. Let's create a new Route for product (ember g route product).

// app/products/route.js

import Ember from 'ember';

export default Ember.Route.extend({
});

We still need a model for our Template; however, this time, rather than returning all products, we want to only return one, based on the value passed in as :product_id. As it turns out, though we usually ignore it, the model function normally accepts an object as an argument (typically called params) which holds data from that route's dynamic segment; if we extract that property from params (:product_id is stored at params.product_id), we can use it to look up the data we want.

// app/product/route.js

import Ember from 'ember';

export default Ember.Route.extend({
  model: function(params){
    return [
      {
        id: 1,
        name: 'Crock Pot',
        manufacturer: 'Farberware',
        price: 40
      },
      {
        id: 2,
        name: 'Food Processor',
        manufacturer: 'Cuisinart',
        price: 25
      },
      {
        id: 3,
        name: 'Electric Griddle',
        manufacturer: 'George Foreman Grills',
        price: 15
      },
    ][params.product_id - 1];
  }
});

Since our Route has a model method, we can now access the data from that method in the Route's corresponding Template.

<!-- app/product/template.hbs -->

<!-- {{outlet}} -->

<h2> Product Details </h2>
<h4>{{model.name}}</h4>
<h5>${{model.price}}</h5>
<p>Manufactured by <em>{{model.manufacturer}}</em></p>
{{#link-to 'products'}}Back to Product Listings{{/link-to}}

Now if we navigate to http://localhost:4200/products/3, we can now see information about the third product on our page.

Since this now works, let's make one final change: replacing the hard-coded HTML in the products template with {{#link-to}} helpers pointing to the specific pages for each product.

<!-- app/products/template.hbs -->

<!-- {{outlet}} -->

<h2> Product Listings </h2>
<ul>
  {{#each model as |product|}}
    {{#link-to 'product' product tagName='li'}} {{product.name}} {{/link-to}}
  {{/each}}
</ul>

Lab: Routing with Dynamic Segments

Let's make employee profiles. Create routes for showing individuals on each team. Those routes should pass employee IDs to the model hooks. You will also need a new template.

Bonus: Refactoring

Move model hook code into a service so that you can re-use it in different routes.

After that's done, the next challenge should be a bit simpler: create an employees route that shows all employees regardless of team, and change the team routes to filter all employees using a dynamic segment.

Additional Resources

Ember Guides - Routing

computingbets/ember-routing-dynamic