Sunday, February 15, 2015

From the Notebook: An Ember Bootstrap Modal Dialog and How to Deal with state in Ember controllers

Bootstrap Modal Dialog for Ember

To create a Bootstrap styled modal dialog for an Ember app at work, I mostly followed the Ember cookbook entry on modal dialogs. One difference is using Bootstrap for the modal dialog, of course. Here are the steps I took.

  1. Added a modal outlet to the application template

    {{outlet modal}}
  2. On my ApplicationRoute.js I have the following:

    actions: {
        openModal: function(modalName, model) {
            return this.render(modalName, {
                into: 'application',
                outlet: 'modal',
                model: model
        closeModal: function() {
            return this.disconnectOutlet({
                outlet: 'modal',
                parentView: 'application'

    This allows me to pass a model to the modal. One implication of this is that the modal view needs to have a corresponding Controller so that Ember can set the model on that Controller. It appears that by default Ember Routes will supply an ArrayController or ObjectController for routes that don't have one defined, but the same doesn't hold for these non-route views.

  3. I then defined a modal-dialog component, but also split out modal-body and modal-footer components since those are the ones I'm expecting to customize from modal dialog to modal dialog.

    <script type="text/x-handlebars" data-template-name="components/modal-dialog">
        <div class="modal fade" tabindex="-1" role="dialog" aria-labelledby="dialogTitle" aria-hidden="true">
            <div class="modal-dialog">
            <div class="modal-content">
                <div class="modal-header">
                    <button type="button" class="close" data-dismiss="modal"
                        aria-label="Close"> <span
                    <h4 class="modal-title" id="dialogTitle">{{title}}</h4>
    <script type="text/x-handlebars" data-template-name="components/modal-body">
        <div class="modal-body">
    <script type="text/x-handlebars" data-template-name="components/modal-footer">
        <div class="modal-footer">
  4. For the component code I need to call .modal() on the modal dialog to pop it up. I also wanted to handle the Bootstrap modal closed event and then remove the modal from the DOM (i.e., disconnect the outlet). Removing the modal from the DOM is not strictly necessary I guess, but I think it is nice to remove it from the DOM when it is no longer needed. If it is rendering a model, there's no point for the hidden modal to re-render when that model changes.

    App.ModalDialogComponent = Ember.Component.extend({
        sendCloseAction: function(){
        didInsertElement: function() {
            this.$('.modal').on('', this.sendCloseAction.bind(this));
        willDestroyElement: function() {
  5. To use it, just need to create a view that uses the modal-dialog component.

    <script type="text/x-handlebars" data-template-name="myModal">
        {{#modal-dialog close="closeModal" title=title}}
                <button type="button" class="btn btn-default" {{action 'save'}}>Save</button>
                <button type="button" class="btn btn-primary" data-dismiss="modal">Close</button>

    One problem I ran into was that Components can only send actions based on names that they are given. My ModalDialogComponent can't call this.sendAction('closeModal') and have that be handled by the ApplicationRoute. Instead ModalDialogComponent calls this.sendAction('close') where the actual named action to send is specified in the view using the component. Here in the myModal template I'm specifying that for close the component should send the closeModal action. See Sending Actions from Components to Your Application for more details.

Ember Controllers Are Singletons

One surprising thing about Ember for me as I've been learning over the past couple months is that Controllers are (kind of, sort of) singletons. Ember instantiates a controller for a route once. So any state in a Controller is sticky. But often times you'll want to reset the state in your Controller when switching from one model to another. So what to do?

Found a couple of interesting blogs regarding this problem:

Both suggest resetting the controller in Route's setupController as one way to address this problem. (Note: Ember.Route also has a resetController hook; haven't used it but seems to cover exactly this need.) Balint Erdi's post has an interesting idea about having the reset logic in the Controller itself and having it observe some property that can be used to trigger a reset.

When thinking about Controller state and Routes, and where to put this state, it occurs to me that there are 3 kinds of view state. A view might want to take advantage of all 3 types of view state.

  1. Transient view state

    This is view state that you don't want to be sticky at all. Maybe expanding/collapsing an accordion type view, or form validation error display.

    Basically, if the model changes, you want to reset this the transient state. For this you can define a resetState function that is called whenever the model changes.

    resetState: function(){
        // reset transient stuff here
  2. Sticky state, but not serialized to the URL

    This would be view state that you want to be sticky so that when the user moves from view to view this state remains. However, for whatever reason, you don't want to serialize this state to a Route URL. This is the default way that Ember works.

    Can't actually think of a good example here. Maybe a sub-view that you expand or show and as you move through different models you want to keep showing that sub-view?

  3. Sticky state that should be serialized to the URL

    If you have some view state that you want to be persistent, then you should really think about moving that to the Route and serializing to the URL. If that works for your use case, then you can do that and move that view state out of the Controller entirely.

To me, #1 is a more common type of view state than #2, so it seems weird that the default for Ember Controllers is #2. However, the fact that Ember Controllers are singletons makes #2 possible and then one just needs to reset state to make #1 work. If Ember Controllers weren't singletons, its hard to see where #2 style view state would be stored.

Odds and Ends

  • Console2: a better Windows console. I played around with setting up Console2 to get a better console window than cmd.exe. The following were helpful resources

    Here's what I like about Console2:

    • You can configure it to copy on select and paste with a right click.
    • You can resize the window (but you have to configure it to have more columns first, which is kind of weird). I sometimes like to have the console take up a full screen.
    • It is tabbed.
    • You can configure it to start a cmd shell or Git bash. I have Git bash as a default and hitting Ctrl+Shift+T opens a new Git bash tab.
  • Ember dot notation. Learned that in Ember instead of doing


    You can do


    If bar is not defined, then the first one would fail but the second would return undefined.

  • Git: counting words in a specific revision of a file. I wanted to be able to count how many words are in a previous version of a blog post. There might be a better way to do this, but here's how I did it.

    1. Get the file's blob hash. You can do

      git log --raw -- path/to/file

      Seems the easiest way. This prints the before and after blob hash for each revision

      :100644 100644 c5d00fe... 2403611... M  path/to/file

      Where 2403611 is the blob hash for this revision and c5d00fe is the blob hash for the previous revision.

    2. cat the blob and count the words. Getting the blob hash was the hard part, now we can simply do

      git cat-file -p 2403611 | wc -w

Sunday, February 08, 2015

Responsive Webapp Conclusions

I've spent a few weeks now reading and thinking about whether it makes sense to use responsive web design techniques to build a single page web application (SPA) that works well on mobile and desktop computers. I started with my initial thoughts and reviewed arguments for responsive webapps and against responsive webapps. I haven't done as much reading as I would like and there is still a lot of good stuff out there to read and learn from. But I think I have learned enough to come to some conclusions.


The first step in deciding whether to go responsive or not with a single page web application is to first design the ideal mobile UI and the ideal desktop UI for your app. Obviously phones and desktop computers have different real estate to work with, but when you are designing an ideal UI for your app think also about the different use cases that users on mobile versus desktop computers will have. Don't just think "how do I make this work on small and large screens". For example, consider an email campaign management app. On desktop the UI would likely be optimized for creating new email messages or templates and bulk loading and editing of email lists. On a mobile device the UI would be more geared to checking the status of email campaigns: open rates, bounceback rates, unsubscribes. Design a UI that makes the most sense for your users on both platforms.

Now, if the UI is basically the same except for layout, then Responsive Web Design techniques could be a good fit. You can use media queries to adapt the layout of the app on different devices.

However, you might still not choose to go responsive. Why?

  1. You might want to optimize what is downloaded on mobile devices. Not only to achieve a smaller download size but also to exclude running JavaScript code that would be a performance burden on mobile devices.
  2. You want the flexibility to diverge the UIs in the future. Sure, today, maybe before you even have any users, you think that the ideal mobile and desktop UIs only differ in layout. But apps should evolve based on feedback from users and as they grow new capabilities. (This point might actually be the nail in the coffin for me regarding responsive SPAs. It seems far more pragmatic to start by having separate mobile and desktop UIs.)
Other recommendations
Only two device classes: phone and desktop (or small and large)

There used to be such a clear cut divide between phones and tablets, but any more I don't see much point in developing separate UIs for them. They share a lot of the same considerations:

  • modest computational resources
  • on mobile networks
  • access to sensors like GPS

I think it is sufficient to just have two device classes.

One thing that does seem reasonable is to use responsive web design techniques to have your mobile UI adapt to larger screen area. For example, you could implement the kind of UI like in the iPad Mail app where in portrait you see only the email message but in landscape you see a list of emails in that folder on the left and the email message on the right.

Also, allow the user to switch between the phone and desktop UIs if they desire. A theme running throughout these blog posts is to try to not make any hard assumptions and this is, to me, one of the big advantages of the device class approach. You might think that the user will best be served by the mobile UI but that user may want the desktop UI. (This also dovetails nicely with thinking about different use cases on mobile and desktop: the user may be on a desktop computer but want to use the mobile UI because it is optimized for the kind of task the user currently has in mind.)

Make everything optimized for touch

Whether you go responsive or take the device classes approach, make everything optimized for touch. Size controls so that they can be tapped on and respond to touch events.

An alternative to responsive webapps: Device Classes

This week I spent some time with Boris Smus' article, A non-responsive approach to building cross-device webapps. As the title suggests, Boris presents an alternative to using media queries and responsive design for building webapps that work on a range of devices. It's a good article and I recommend reading it. In this blog post I'll review his arguments and give my thoughts on the matter.

To start with, Boris sees a few problems with Media Queries (or at least, with using just media queries to adapt layout for different screen sizes):

  • All devices get the same assets: the same JavaScript, CSS, images etc. So there is a good chance that devices are downloading a lot more than they would absolutely need to.
  • All devices start with the same DOM. To get the DOM to look one way on one device and look another way on a different device could lead to overly complicated CSS.
  • Not much flexibility to customize the UI for different types of devices. You can do it with a media query approach but if you have a mobile view that is just completely different from a desktop view, you will have duplicate views and the application code has to be careful to handle both views at once, depending on screen size. That is, while creating a custom view for a certain type of device, you have to think about how it will work for all other types of devices.

Smus recommends developing separate UIs for three different device classes:

  1. mobile phones (small screen width + touch)
  2. tablets (large screen width + touch)
  3. desktops (no touch)

He suggests using device width and whether the device is touch enabled to distinguish between these device classes. How reasonable are these criteria?

As one of the commenters mentions, hindsight is 20/20. We live in an era of touchscreen desktop Windows 8 computers, and they don't appear to be going anywhere. We can no longer assume that lack of touch support equals desktop or vice versa. One of my big takeaways from this whole investigation is that all controls should be designed to be touch friendly.

What about the small screen/large screen divide? As I wrote in my previous post, we now have many large phones and small tablets such that the height of a large phone can easily exceed the width of a tablet. I still think a line can be drawn somewhere and I do think that it is useful to design a mobile friendly version of a webapp. But that line is continually moving and blurring.

Okay, now that we have 3 device classes (personally I only see two: mobile and desktop), what does Smus recommend for detecting and serving up these different experiences? Smus compares doing server side and client side detection and comes down on client side detection, mostly because it is feature detection based (more future proof) instead of user agent based. I agree there.

Smus suggests using Device.js (apparently one of his open source projects) to do this client side detection.

He also suggests using a MVC framework and only making separate View classes for the difference device classes. This allows you to get a lot of reuse while also being able to fully tailor the UI for a particular device class.

Overall, I'm impressed with this approach. If your application is best implemented with a different UI on mobile versus desktop, I think this is probably the best approach. Responsive Web Design seems to be a good fit only when the UI is basically the same on mobile and desktop with only the layout needing to be a little different. For example, at Walker Information, we have a survey application. On mobile and on desktop, the essential UI is the same, with only layout differing. Each page has a list of questions and controls for providing answers, with Back and Next buttons to navigate through the survey. This is a good candidate for being designed responsively. As a counter example, consider something like a webapp for MailChimp. On desktop it might be optimized for creating emails and setting up campaigns whereas on mobile the UI might be quite different and be focused on monitoring open rates, bounceback rates, etc. In this case, having two completely different apps would be a better fit.

There are some downsides with this separate app for device classes approach:

  • If the device class is part of the URL then bookmarks, shared links would include it as part of the URL. It would be nice to have canonical URLs.
  • Separate views for the device classes is extra work and has its own maintenance overhead
  • Doesn't respond to orientation changes or browser resizing
    • However, it would be possible to combine both approaches. You might create a separate view for the mobile device class that itself uses media queries to adjust the UI between phone-like sizes and tablet-like sizes.

On a closing note, there is one other thing I like about Smus' approach. He recommends having links in the app to the different device classes. This way if you are on a mobile phone and really want the desktop view, you can get to it. I think this is in line with the thinking from the last blog post that challenges the consensual hallucination that we as web developers tend to participate in. Our assumption about what is mobile, what is a desktop computer are being challenged all the time. It would be good to make fewer assumptions. Letting a user switch to a non-default device class, to me, fits in with that line of thinking. We only have a limited understanding of the kinds of devices that exist today. Hopefully the devices that arrive in the future will surprise us and challenge our assumptions. And hopefully our webapps will be ready.

Additional Resources:

  • Really liked this post by Brad Frost that Smus links to. He makes the point that while media queries are great, the most important thing to optimize on mobile is performance.

Sunday, January 18, 2015

Researching Responsive Webapps

In a previous post I wrote about my initial thoughts regarding responsive Single Page Applications (SPAs). I've now done a bit of digging to find out what other folks think about this topic.

Among the blog posts I read I found Jason Grigsby's series of blog posts Responsive Design for Apps especially interesting.

Consensual Hallucination

In the first blog post in this series, Jason makes the case that web developers and web UI framework authors have been participating in a consensual hallucination regarding what phones and tablets and desktop computers are limited to, just as we once assumed desktop browsers were 960 pixels wide. Web UI frameworks tend to have a library of mobile widgets (e.g, jQuery Mobile) and a separate library of desktop widgets (e.g. jQuery UI). The reasoning given by framework authors is that phones and tablets and desktops are fundamentally different platforms. But what are these fundamental differences? A cellular radio? The answer isn't clear and Jason is dubious that a good answer exists.

Jason looks at the size of phones and tablets and points out that the height of the larger phones out there easily exceeds the width of the smaller tablets available. His article was published in early 2013 and since then the gap has only narrowed. In fact Jason at one point says

The small gaps that exist are either things that seem inevitable (high-dpi on large screens) or are so small to be inconsequential (does it matter that we don't have six inch displays?).

And of course, we now have 6-inch phones and 6-inch tablets.

There's no clear line between phones and tablets, but what about desktops? We used to be able to assume that touch was a fundamentally distinct mode of interaction on mobile devices. However, Windows 8 and all of the touch screen desktop and laptop products that are built for it obliterates that assumption. He points to research to suggest that touchscreen desktops are not a fad. I've yet to have a chance to play with a Windows 8 touchscreen device myself but I agree. I have to believe that eventually Apple will have to catch up too.

One of the key takeaways for me from this article is that every application should be designed for touch interaction. Primarily this means making targets big enough to be easily tapped on with fingers. Because of Fitts's Law, desktop users using a mouse will also benefit because these larger targets are easier to hit.

Making desktop app responsive

In Jason's second post he looks at a typical desktop app and tries to reimagine it as a responsive web app.

One of the problems he ran into is that if you take a desktop app design and try to make it responsive, you kind of run into a brick wall. He starts making progress when he takes a mobile first strategy. He designs a version of the web app that is optimized for mobile.

Once he has an optimized mobile design, he then looks at how it maps to the desktop app and finds that it maps pretty well. That's important for a responsive web app; each screen in the mobile design needs to be able to map to a corresponding screen in the desktop design. If there isn't a mapping, that is, if the mobile design is not just a different layout compared to the desktop design, then responsive web design probably won't work.

Finally, he takes another look at the desktop design and rethinks it in terms of the mobile design. This is also an important step in evaluating if responsive web design is feasible. For the mobile design he had to compromise in some places and display less information than on the desktop design. So its important to step back and look at if these mobile design components can be used in the desktop design.

Desktop and mobile design patterns

In the third part of the Jason's series Jason looks at how desktop operating systems have been incorporating mobile design ideas. In particular he looks at Apple's Mail app on iPhone, iPad and Mac OS X.

The iPhone Mail app uses a nested doll design pattern: moving froma list of items to greater detail or sub-lists of that item. On the iPad, we see a slightly different pattern, what has been called the bento box pattern: the list of email messages is displayed on the same screen as the detail. The iPhone and iPad app actually share views (for example, mail accounts and folders listing screens).

On Mac OS X, the Mail app there shares a lot of similar design elements although it does have a different look. One could definitely imagine there being a single Mail app that runs across all Apple devices and that adapts to the available screen real estate.

To me it is a little bit of stacking the deck to use the Mail app. Because information in the Mail app is arranged hierarchically (mail accounts list, folders list, messages list), it is not too hard to design a responsive Mail app. But not all apps are so simple. Word processing apps tend to have a main content area and several controls for affecting layout and formatting. A mobile word processing app design would be quite a different design, not likely to share much with its desktop counterpart.

Also, Jason only looks at views that display lists of accounts and emails and the views that display the email itself. That is, he only considers the views related to reading email. The desktop Mail app includes formatting options and stationary options when composing email, which would take up too much real estate on mobile. This is because on mobile users are typically more interested in reading and filing and flagging and deleting email. On mobile users only need to be able to write short responses, typically. On desktop the email composing needs are very different.

Nevertheless, I think his conclusion that

responsiveness for apps is inevitable

is mostly true. Responsive web design can be a good fit for some apps and even apps that are better served by different UI designs on mobile and desktop will benefit from responsive design techniques on mobile (for example a mobile UI that responds to more real estate on a tablet versus a phone).


I find Jason's arguments compelling. The idea that phones are fundamentally different from tablets and desktops and so require different UI frameworks and separate apps is undermined by the evidence that not much actually separates these different devices in terms of technical capability.

However, one thing that I think is missing a little from the discussion is how these different devices are used and what they are used for. Yes, technically, there isn't much difference between phones and tablets and desktops except screen size. On the other hand, users on mobile devices may have different tasks in mind that they want to accomplish versus users on desktop devices. As I mentioned above regarding the Mail app example, mobile users mostly want to read and deal with email by flagging, filing, deleting etc. Composing longer or more format heavy emails are saved for when the user is at a desktop computer. Now, this isn't a big difference in goals for mobile and desktop users for this particular app, but for certain apps mobile users may have very different goals from desktop users. This needs to be kept in mind when designing optimal desktop and mobile UIs. I'll expand on this a bit in future posts, but to me this is one of the most important reasons why you might want separate mobile and desktop apps.