All You Need is CRUD?

Posted by Tom on 2006-11-17

DHH, as you probably heard, has learnt to stop worrying and love the CRUD. I’m very much in agreement. The idea of replacing the actions add_member and remove_member (or would that be join_group and leave_group?) with Membership#create and Membership#destroy was the final light switch that got me to a place I’d been striving for.

The generic controller. A standard implementation of the CRUD actions that can be used out-of-the-box in a large majority of cases.

The idea is that the concrete controllers that make up an application will need no custom code at all – just a few declarations: I need an auto-completer for this attribute, an ajax-setter for that one… I don’t see why this can’t be done.

Of course if an application needs to do something unusual, then sure you might want a custom action or two. But a huge number of apps are really nothing more than a web-interface to a database, and nearly all apps have at least some parts that fit this description.

There are a couple of challenges though. Firstly, what should these standard actions render? It’s all very well to have a single URL that you hit to, say, create a new event in your calendar, but depending on where in your app you’re coming from, you’re likely to want a different page (or ajax update) to follow.

Simple answer - parameterise it. Have the browser request “create me a new event, then refresh parts a, b, and c of my page”. That functionality is now part of Hobo and seems to work great. As well as getting us closer to a fully generic controller, this idea has also yielded a very simple approach to ajax.

Another problem I’ve hit is that sometimes an application feature requires a whole graph of related models be created in one go. The solution to that one has been to extend the way ActiveRecord handles the hash you pass to With Hobo’s ActiveRecord extensions, that single call to new can set up arbitrary relationships with other models, either existing or new.

This post is light on technical details (all will be revealed), but it sets the stage for what I want to waffle about next – Hobo’s support for ajax. I think Hobo’s approach will make ajax programming easier than with anything else out there.

Just had a good week delivering a Rails training course for Skills Matter in London, but of course that meant little progress with Hobo. Next week it’s full steam ahead!