Do transactions re-associate detached objects?

It appears that wrapping a manager method in a transaction via Hibernate's AOP functionality, does not automatically re-associate any detached objects passed into the method to the session. You'll need to do this manually.

A Spring WebFlow Gotcha

If your flow definition has a element and its "if" attribute contains two or more clauses joined by the AND logical connector, make sure to use & amp;& amp; (no spaces) instead of &&, because && breaks XML validation.

Hibernate Intricacies

Forgive me please if the following post is not 100% clear.

Imagine this: You've got a Proposal object with a List<Resource> field. Each Resource has a Map<ResourceAttribute> field. You're using Hibernate, and the Resource.hbm.xml contains a <map> element with cascade="all-delete-orphan". If you call Session.save(resource) for a particular resource belonging to a proposal, and later call Session.update(proposal) for that proposal, you will get the following exception - Don't change the reference to a collection with cascade="all-delete-orphan".

Obviously you haven't directly changed the resource's reference to its map of attributes, but, somehow, by saving the resource directly, instead of jumping up a level and saving the proposal to which it belongs, you're causing Hibernate to consider the reference changed.

Extending JavaScript's onsubmit method

Suppose your page has a form, and you want to extend its onsubmit method programatically. Here's one way to go about it:

form = document.getElementById("form");
form.realSubmit = form.onsubmit;
form.onsubmit = function () {
  alert("before the original onsubmit");
  this.realSubmit();
}

(Based on Orc Scorcher's response to this thread on www.webdeveloper.com)

A Queue of AJAX Requests

Till now, I hadn't written code to fire off a number of AJAX requests with callbacks in rapid succession. The code wasn't working as hoped, and usually only the last callback would succeed. This is because a new AJAX request is being made before the callback for the previous request has finished executing. Due to their being only one XMLHttpRequest, concurrency issues prevail. A possible solution involves creating a queue for the requests and only firing the next request once the callback for the previous one has completed.

Javascript tip

This one had me stumped for 30 minutes or so. When including a JavaScript file in your HTML, make sure you provide open and close script tags. The abbreviated single tag with a backslash at the end doesn't work. At least in Firefox 3.5.4.

Tip: Spring Webflow 2.0

Unlike the flowExecutionUrl variable which is exposed in your JSP and can be used like so - ${flowExecutionUrl} - the messageContext variable is not exposed.