From bf6507297e46dd38ddba7c49fe8ea25ae8a5e6fc Mon Sep 17 00:00:00 2001
From: José Mota <josemota.net@gmail.com>
Date: Thu, 13 Dec 2012 20:09:20 +0000
Subject: New post: Your ember is a click away from home

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+---
+layout: post
+title: Your Ember app is a click away from home
+tags: [ ember, development ]
+published: true
+---
+I've been having some time to explore Ember.js lately and I wanted to learn by
+doing instead of just reading about it. So bear with me as this might probably
+require some updating in the future. This is a result of trial and error and I
+thought of making the Ember learning curve a little easier and share this tip.
+
+So I've been trying to build a simple application that manages pictures. I
+started the good ol' fashioned way of manually calling all the scripts and
+declaring all the templates from the index page, for argument's sake. I would
+much rather have something like
+[Iridium](http://github.com/radiumsoftware/iridium) to help with my development
+process but I had faced some trouble with it before.
+
+My first step: list of pictures
+-------------------------------
+
+The first thing that came to my mind was to have a list of pictures and allow
+the user to add a new one by clicking on a link that would transition to
+something like `/pictures/new`. In the pictures list template I would have
+something like:
+
+{% highlight html %}
+<h2>Images</h2>
+{%raw%}{{#each image in controller}}
+  <li>{{image.title}}</li>
+{{/each}}
+<p>
+  <a {{action newImage href="true"}}>New image</a>
+</p>
+{%endraw%}
+{% endhighlight %}
+
+The link in the paragraph goes to the route transition in "root". Let me give
+you the router so you can better understand what I'm saying:
+
+{% highlight javascript %}
+Exhibit.Router = Ember.Router.extend({
+  root: Ember.Route.extend({
+  , index: Ember.Route.extend({
+      route: "/"
+    , connectOutlets: function(router, context) {
+        router.get("applicationController").connectOutlet("images", Exhibit.Image.all());
+      }
+    , newImage: Ember.Route.transitionTo("newImage")
+    })
+    , newImage: Ember.Route.extend({
+        // ...
+      })
+  })
+});
+{% endhighlight %}
+
+Inside the `index` route, the `newImage` path points to the `newImage` route
+which will print a form.
+
+The challenge: Going back home
+------------------------------
+
+At this point in time, I was curious as to the possibility of aborting the
+process of creating a new image and simply going back home and start over. As I
+was learning, I realized that actions in the templates point to routes in the
+router as a way to acknowledge an application state change. I faced the
+challenge of wanting to leave the form and go back and not being able to
+do it.
+
+I recalled that actions should be defined in the state (the route) the
+application is in. Clicking on the `newImage` link transitions my app to the
+`root.newImage` state. So I thought of doing something like this in the router:
+
+{% highlight javascript %}
+Exhibit.Router = Ember.Router.extend({
+  root: Ember.Route.extend({
+  , index: Ember.Route.extend({
+      // ...
+    })
+    , newImage: Ember.Route.extend({
+        route: "/new"
+      , connectOutlets: function(router, context) {
+          // connect the outlet
+        })
+===> , goHome: Ember.Route.transitionTo("root.index")
+    })
+  })
+});
+{% endhighlight %}
+
+This looks rather trivial and probably won't make the point alone. What I
+thought at the time when I wrote this was _should I really need to write this
+transition in every single route?_ After all, going back home should be
+possible for every action, every state in the app.
+
+The solution: Use the state machine
+-----------------------------------
+
+After some trial and error, I ended up with this:
+
+{% highlight javascript %}
+Exhibit.Router = Ember.Router.extend({
+  root: Ember.Route.extend({
+=>  goHome   : Ember.Route.transitionTo("root.index")
+  , index    : Ember.Route.extend({ /* ... */  })
+  , newImage : Ember.Route.extend({ /* ... */ })
+  })
+});
+{% endhighlight %}
+
+Since the router is a state machine, when defining the `root` route, I'm able
+to add state changes there that will be inherited for every sibling state in
+that tree. Both `index` and `newImage` and all the routes that are defined in
+`root` will have this state change available.
+
+This was a finding for me as I have never grasped the concept of state machines
+like this.
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