Thursday, November 5, 2009

Hacking Oracle APEX IR reloads

Writing is hard and I am lazy. Here's another try, however.

Over time, our internal APEX framework acquired a few features that are quite nice. For some of them, we had to find workarounds for stuff that isn't directly supported. Thankfully, on the server side the APEX engine can be influenced (e.g. variables in package wwv_flow) and JavaScript/CSS can manipulate the display and behaviour on the client side. The former is totally unsupported/undocumented and the latter to a certain part, however. As long as it works we can live with that, because our applications will run on intranets where we can control the environment.

The latest hack had to do with interactive reports. To implement a feature (right-mouse popup over some columns, metadata-driven content), we had to run JavaScript code on the client that modified the IR table's HTML. It worked pretty well except after AJAX refreshes, which of course are integral to IRs. The APEX AJAX code replaced the HTML table including my code's changes with new one from the server. The older partial page refreshable reports called init_htmlPPRReport which could be overwritten to put the changes back in again (see here) but no such luck with IRs. After wading through the code of apex_ns_3_1.js I found out that the refresh code called $x_Show('apexir_REPORT') at the end. I overwrote that and now everything works.

So, what's the bottom line? I think Oracle would do developers a great favour if they included standardized and supported hooks for extension writers to plug their code in. For my example above, say, there might be a JavaScript function

apex.hooks.after_region_reload = function(i_region_id) {}

that gets called after partial page refreshes and could be overwritten. Better, make that an Array of functions, initially empty, so we can

function(i_region_id) {
alert("do something extension specific");

Patrick, can you hear me? *g*