Raible Designs

Ajax on Rails with Stuart Halloway

There's a number of presentations I'd like to attend during this time slot. In particular, I'd like to attend Testing with Selenium and Simplified Ajax Development in Java with ICEfaces. However, Stuart Halloway is an excellent speaker and I'd rather hear him talk than learn something in another session. Hopefully other attendees blog about the aforementioned sessions so I can still learn something from them.

Agenda: Ajax, Libraries for Ajax (i.e. Prototype and Scriptaculous), Rails and Ruby.

There's probably 100 people in the room. Stuart did a survey of who is using Rails - I'd say the response was about 10%. He also asked who's considering it for future development. The response seemed to be around 25%. I'm sitting in the front of the room, so I probably didn't see the results as well as Stuart did. Regardless, it's interesting to see that most people in the room won't be using Rails, they're merely interested in it (or they wouldn't be in the room, right?).

The best way to play with Rails on Windows is called InstantRails. For OS X, there's Locomotive.

All the demos given during this session are available in the ajax_labs section at codecite.com.

Things we're going to look at: autocomplete, in-place Editing, searching, sorting, expando, drag and drop, sort, server-side validation, client-side validation, and prototype windows (Stuart prefers to call them divdows).

Stuart is talking a lot about how Rails works at this point, model objects, yml files, tests and sample data. One of the things that I find interesting about most CRUD-generation frameworks is they don't take tests into account. Ruby on Rails generates tests, so does AppFuse. If you work on a CRUD-generation project for web development, do you generate tests too? If not, don't be embarrassed, tell us. There has to be a good reason you're not doing this.

Now the audience is struggling with the concepts in Rails, how ActiveRecord works, etc. For example, one guy asked if it's possible to use JDBC with Rails. It's definitely a humorous question, but Stuart handled it quite well without ridiculing the guy. A couple of notes: Rails doesn't work well with stored procedures or composite keys.

Now we're looking at the view layer, in particular a show.rhtml template. It's pretty simple , but not very HTML-ish. Looks a lot like scriplets in JSPs. Autocomplete with Rails is mostly CSS-driven. To use it in a Rails view, you start with the following line of code at the top of your template.

<%= stylesheet_link_tag 'autocomplete' %>

In Rails, when you want to render an Ajax response in a controller, you use the following at the end of your method.

render :layout=>false

This turns off any page decoration. It'd be nice to have something like this in the Java world - so you could turn off page decoration from SiteMesh, Tiles, etc. It shouldn't be hard to implement this in SiteMesh, but it might take a bit of work for Tiles.

Partials are Rails' way of creating fragments that are designed to be populated and returned by Ajax calls. Their naming convention is to being the filenames with an underscore. For example <%= render :partial=>'search' %> looks for a _search.rhtml template.

For Ajax development with Rails, you're not tied to using Prototype or Scriptaculous. However, since Rails has helper methods that emit the JavaScript, it makes things much easier. If you'd like to use Dojo, you'd have to hand-code the JavaScript into your RHTML templates, or write helper methods for Dojo. Stuart would like to see a Rails plugin that allows you to switch the Ajax helpers from one library to the other.

The last thing Stuart showed was Prototype Windows. This looks similar to lightbox gone wild, except you get better styling around the modal window. If you haven't heard enough of what Stuart has to say, checkout blogs.relevancellc.com. One of the most interesting things lately is he's been posting reviews of the various Ajax books.