Taconite

I'm working with a jQuery plugin called Taconite (not sure how to pronounce it, is it a soft C or hard C, long A or short A?) that is very handy for doing a whole bunch of jQuery commands with an AJAX request. Basically what you have to do is use XML, and the XML tags are the commands that you want to be executed.

There are a few things that I really like about it. First off, it makes it easy to have multiple updated divs. See with a regular updater object (like in Prototype) you can specify a URL and an HTML element ID, and it will dump the result of an AJAX request into that HTML element. Fairly handy. Taconite takes it two levels higher in that you can dump parts of the result in say three HTML elements, or seven thousand. You do this by passing a jQuery selector as a target, so if you go ".pickles", it replaces all HTML elements that have a class "pickles". Nice.

There's more than just replacing that you can do. Suppose you want to hide an element:

<hide select = "#thingy-id" />

All sorts of other commands can be used. Makes it nice and easy to do fancy stuff. You can also use <eval> tags to execute random Javascript.

The icing on the cake is that it is all automatic. You just have to include the Taconite js file, and all your AJAX requests will be Taconite-enabled. However, this doesn't mean every one will be processed by Taconite, only if it is XML-valid (perfect enforcer of standard XHTML) and it contains the <taconite> tag. Other than that, nothing happens - which is slightly annoying at times if you haven't managed to get your XHTML right, but that's what a validator is for.

So using this led me to some issues with Rails. How do we serve up XML? It's fairly easy, you just have to specify it. Go like this:

respond_to |wants|
  wants.xml
end

And Rails will look for action.xml.erb. Easy enough. The next problem is a little trickier, although the solution is fairly simple and intuitive. Since some of the "XML" that is put into this file is actually XHTML (it better be XHTML, or you're gonna be having headaches - remember to put the / in <img />) you're going to have to be coding part of your view in the Taconite XML file. It works just fine with the eRuby stuff, just code like you always have. The problem will come once you start trying to render partials in your XML file. Suppose you go

render :partial => "mypartial"

Since you're currently rendering XML, Rails will look for _mypartial.xml.erb, which may or may not exist. For me, the partials that I wanted to render in the XML were also being rendered in HTML files elsewhere in the app. Now the first option is to just copy the file from _mypartial.html.erb, but then we have code duplication which is so not cool dude. Maybe we could use a symlink, but that seems rather hackish and won't work if someone on your team is using Windows - speaking of which, I should write another article on Linux at work, seeing as how I haven't used Windows for work in over two months. The solution is very easy. Instead of the regular render statement, you go like this:

render :partial => "_mypartial.html.erb"

And it will work. Now you can have your cake and eat it too.

I just realized something, I haven't posted an article about how jQuery is so much more awesome than the other Javascript libraries I've used (Prototype/Scriptaculous or Mootools). More on this another day.