Scott Williams’s Ramblings

I like frameworks. I spent far too much time in my programming infancy reinventing the wheel, and I don’t want to ever have to write more code than I have to again. Thus, I like relying on frameworks to take the tedium out of certain parts of the craft.

However, a problem arises when you don’t know what that framework is doing. Recently I spent many hours tracking down one specific bug that needed a single line changed to fix. In this specific case it was in an ASP.NET WebForms app. A <button> tag was used to make some fancy ajaxy calls via jQuery and PageMethods and the onclick event. The problem was that the form that was supposed to be displayed only appeared for a few seconds, then vanished again.

I poured through the code, set many breakpoints, broke out both Firebug and the Safari debugger (both proved useless due to the actual problem). Despite all of this, I still couldn’t figure out what the heck was going on. Finally, after I was ready to jump off the parking garage, the light bulb clicked on.

The <button> tag behaves like <input type=”submit” />; it sends a postback. And since the form was wrapped in an UpdatePanel, it was executing both the jQuery ajax, as well as the ASP.NET ajax, which were clobbering each other. In Firefox, the jQuery code finished first, and was then overwritten by the Page_Load from the UpdatePanel, causing our freshly rendered form to go away.

Changing the <button> to <input type=”button” /> fixed things. There are plenty of other fixes for this issue, but that’s what we used.

ASP.NET WebForms and ASP.NET Ajax like to abstract many of the “complicated” web development concepts away from the developer. I’m not going to comment on whether this is a good or bad thing, but it can present issues if you are using some mechanism and are not aware of what is going on under the hood. These problems usually don’t even manifest until late in a project- when the bosses are breathing down your neck and wondering why the app isn’t finished yet.

Does this mean we should abandon frameworks entirely and code everything in C (or assembler)? Certainly not, but if you are going to use that extra super duper happy UpdatePanel, you had better know what it is going to do to everything inside of it.