How Can The Current Route Be Observed for Changes?

Question

I want to update the <title> tag for the page whenever the location (route) changes. I'm particularly interested in observing App.Router's current route changing - I then want to access the View associated with that route and update the <title> tag from the observer based on a property of the View.

For example, if going to /about

1. What do I set the Observer to observe? I'm having trouble finding a currentState property or equivalent to observe.
2. Within the Observer, how can I access the App.AboutView associated with the route?

I'm using 1.0.0pre4

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My goal is to have a title property and an authorization property on each View that the Observer on currentPath will work with. I want to use the title property to update the document.title, and the authorization property object to check wither my current user can access the route.

Now that I say this and with @Michael Grassotti's answer, perhaps these properties belong on the Controller and not the View. The goal is to gain access to these properties associated with the current Route's context to modify the document.title and check whether or not my App.CurrentUserController (that stores a User object model for the logged in user) is authorized to acess the current route.

Camass

Answer 1

So the properties I'm trying to work with belong on the Controller for the route, not the View.

Given some contactUs route, it's Controller might look like

App.ContactUsController = App.AppController.extend({
  title: "Contact Us"
});

My App.ApplicationController can now look like

App.ApplicationController = Ember.Controller.extend({
  updateTitle: function() {
    window.document.title = this.controllerFor(this.currentPath).get('title');
  }.observes('currentPath')
});

So the API methods/properties I was looking for are

• App.ApplicationController.get('currentPath') (currently appears to be undocumented on the site)
• controllerFor (also seems undocumented, but is found within a reopen implementation for Ember.ControllerMixin)

Camass

I couldn't get this to work with Ember 1.13, but found that the reopening the router and observing the on('didTransition') event as described here worked: https://mcmap.net/q/724861/-ember-js-route-hook-to-be-called-on-every-transition – Aplanatic

Answer 2

1. What do I set the Observer to observe? I'm having trouble finding a currentState property or equivalent to observe.

You can observe the ApplicationController.currentPath. For example:

App.ApplicationController = Ember.Controller.extend({
  currentPathDidChange: function() {
    path = this.get('currentPath');
    console.log('path changed to: ', path);
    window.document.title = path;
  }.observes('currentPath')
});

1. Within the Observer, how can I access the App.AboutView associated with the route?

Trying to access App.AboutView from this observer would be tricky and probably not a good idea. I'm not clear on why a view's property would be useful in this scenario. Can you elaborate?

Cris

Thanks for the reply; I updated my Question to give more context. – Camass

I have sorted out the other half of the problem. Thanks for the nudge with currentPath. – Camass

No problem. Totally agreed re: your conclusion above, these properties belong on the controller. – Cris

Can you do something like this on a view? – East

Sure. From applicationView it would be observes('controller.currentPath') – Cris

Im setting a property in my controller whenever the route changes it gets updated. However the issue is that on a dynamic segment it doesn't change the route so currentPath won't work. I need to observe this change in order to update this property. The closest I have come is this #16471568 However if I place App.Router.router.generate(['posts.new']); in the observer it still doesn't fire. Any ideas? – Aurita

would it be possible for a component to observe this route change without extending the ApplicationController? – Molybdenous

If I create this controller in an addons app folder, how can I get it to merge with the ember cli apps own appController? – Molybdenous