Services

Services can be generated using Ember CLI's service generator. For example, the following command will create the ShoppingCart service:

ember generate service shopping-cart

Services must extend the Ember.Service base class:

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

Like any Ember object, a service is initialized and can have properties and methods of its own. Below the shopping cart service manages an items array that represents the items currently in the shopping cart.

export default Ember.Service.extend({
  items: null,

  init() {
    this._super(...arguments);
    this.set('items', []);
  },

  add(item) {
    this.get('items').pushObject(item);
  },

  remove(item) {
    this.get('items').removeObject(item);
  },

  empty() {
    this.get('items').clear();
  }
});

To access a service, you can inject it in any container-resolved object such as a component or another service using the Ember.inject.service function. There are 2 ways to use this function. You can either invoke it with no arguments, or you can pass it the registered name of the service. When no arguments are passed the services is loaded based in the name of the variable key. You can load the shopping cart service with no arguments like below.

export default Ember.Component.extend({
  //will load the service in file /app/services/shopping-cart.js
  shoppingCart: Ember.inject.service()
});

The other way to inject a service is to provide the name of the service as the argument.

export default Ember.Component.extend({
  //will load the service in file /app/services/shopping-cart.js
  cart: Ember.inject.service('shopping-cart')
});

This injects the shopping cart service into the component and makes it available as the cart property.

Injected properties are lazy loaded; meaning the service will not be instantiated until the property is explicitly called. Therefore you need to access services in your component using the get function otherwise you might get an undefined.

Once loaded, a service will persist until the application exits.

Below we add a remove action to the cart-contents component. Notice that below we access the cart service with a call tothis.get.

export default Ember.Component.extend({
  cart: Ember.inject.service('shopping-cart'),

  actions: {
    remove(item) {
      this.get('cart').remove(item);
    }
  }
});

Once injected into a component, a service can also be used in the template. Note cart being used below to get data from the cart.

<ul>
  {{#each cart.items as |item|}}
    <li>
      {{item.name}}
      <button {{action "remove" item}}>Remove</button>
    </li>
  {{/each}}
</ul>