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Ember.js action helper and routing.

#Relevent parts to explain action, routes in Ember 1.0pre

##Action Helper The {{action}} helper registers an HTML element within a template for DOM event handling and forwards that interaction to the Application's router, the template's Ember.View instance, or supplied target option (see 'Specifiying a Target'). User interaction with that element will invoke the supplied action name on the appropriate target.

(Example without Router skipped, check helpers/action.js)

Specifying a Target

There are several possible target objects for {{action}} helpers: In a typical Ember.Router-backed Application where views are managed through use of the {{outlet}} helper, actions will be forwarded to the current state of the Applications's Router. See Ember.Router 'Responding to User-initiated Events' for more information. If you manaully set the target property on the controller of a template's Ember.View instance, the specifed controller.target will become the target for any actions. Likely custom values for a controller's target are the controller itself or a StateManager other than the Application's Router. If the templates's view lacks a controller property the view itself is the target. Finally, a target option can be provided to the helper to change which object will receive the method call. This option must be a string representing a path to an object:

<script type="text/x-handlebars" data-template-name='a-template'>
  <div {{action anActionName target="MyApplication.someObject"}}>
    click me
  </div>
</script>

Clicking "click me" in the rendered HTML of the above template will trigger the anActionName method of the object at MyApplication.someObject. The first argument to this method will be a jQuery.Event extended to include a view property that is set to the original view interacted with.

A path relative to the template's Ember.View instance can also be used as a target:

<script type="text/x-handlebars" data-template-name='a-template'>
  <div {{action anActionName target="parentView"}}>
    click me
  </div>
</script>

Clicking "click me" in the rendered HTML of the above template will trigger the anActionName method of the view's parent view.

The {{action}} helper is Ember.StateManager aware. If the target of the action is an Ember.StateManager instance {{action}} will use the send functionality of StateManagers. The documentation for Ember.StateManager has additional information about this use.

If an action's target does not implement a method that matches the supplied action name an error will be thrown.

<script type="text/x-handlebars" data-template-name='a-template'>
  <div {{action aMethodNameThatIsMissing}}>
    click me
  </div>
</script>

With the following application code

AView = Ember.View.extend({
  templateName; 'a-template',
  // note: no method 'aMethodNameThatIsMissing'
  anActionName: function(event){}
  });

aView = AView.create();
aView.appendTo('body');

Will throw Uncaught TypeError: Cannot call method 'call' of undefined when "click me" is clicked.

Injection of Controller Singletons

During application initialization Ember will detect properties of the application ending in 'Controller', create singleton instances of each class, and assign them as properties on the router. The property name will be the UpperCamel name converted to lowerCamel format. These controller classes should be subclasses of Ember.ObjectController, Ember.ArrayController, Ember.Controller, or a custom Ember.Object that includes the Ember.ControllerMixin mixin.

App = Ember.Application.create({
  FooController: Ember.Object.create(Ember.ControllerMixin),
  Router: Ember.Router.extend({ ... })
  });

App.get('router.fooController'); // instance of App.FooController

The controller singletons will have their namespace property set to the application and their target property set to the application's router singleton for easy integration with Ember's user event system. See 'Changing View Hierarchy in Response To State Change' and 'Responding to User-initiated Events.'

Responding to User-initiated Events

Controller instances injected into the router at application initialization have their target property set to the application's router instance. These controllers will also be the default context for their associated views. Uses of the {{action}} helper will automatically target the application's router.

Given the following application entered at the URL '#/':

App = Ember.Application.create({
  Router: Ember.Router.extend({
    root: Ember.Route.extend({
      aRoute: Ember.Route.extend({
        route: '/',
        anActionOnTheRouter: function(router, context) {
          router.transitionTo('anotherState', context);
          }
      })
      anotherState: Ember.Route.extend({
        route: '/differentUrl',
        connectOutlets: function(router, context) {

        }
     })
    })
  })
});
App.initialize();

The following template:

<script type="text/x-handlebars" data-template-name="aView">
 <h1><a {{action anActionOnTheRouter}}>{{title}}</a></h1>
</script>

Will delegate click events on the rendered h1 to the application's router instance. In this case the anActionOnTheRouter method of the state at 'root.aRoute' will be called with the view's controller as the context argument. This context will be passed to the connectOutlets as its second argument.

Different context can be supplied from within the {{action}} helper, allowing specific context passing between application states:

<script type="text/x-handlebars" data-template-name="photos">
  {{#each photo in controller}}
    <h1><a {{action showPhoto photo}}>{{title}}</a></h1>
  {{/each}}
</script>

See Handlebars.helpers.action for additional usage examples.

Ref 1: https://github.com/emberjs/ember.js/blob/master/packages/ember-routing/lib/router.js

Ref 2: https://github.com/emberjs/ember.js/blob/master/packages/ember-handlebars/lib/helpers/action.js

@sh4n3d4v15

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@sh4n3d4v15 sh4n3d4v15 commented Jan 3, 2013

Nice work, really helpful! :)

@sly7-7

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@sly7-7 sly7-7 commented Jan 3, 2013

This is indeed a good job, unfortunately this is already outdated, since the new router api. See http://emberjs.com/guides/routing/defining-your-routes/

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