PostgreSQL (often called Postgres) is the Other Major Database for Drupal. It has one of the same strange characteristics that Drupal does: its adherents swear that it is the best thing since sliced bread. In this article, we'll examine how to get PostgreSQL installed, then get a Drupal 6 installation running on top of it.

Assumptions: XCode Tools from your Mac OS X DVD (also available from Apple Developer Connection) are installed. Your copy of PHP has support for Postgres (I used MAMP and it worked out of the box).

Building a Drupal module from scratch can be remarkably simple -- just create an .info file, create a .module file, then implement a few functions like hook_menu and hook_nodeapi. In no time, you've got a module up and running, leveraging Drupal's APIs and adding functionality to your site.

The problem

Unfortunately, things can get a bit more complicated if your module needs to store and maintain its own collection of data. The Custom Links module, for example, allows users to add clickable links to the bottom of each node on a Drupal site. While the code to actually add the links to each node is only a few dozen lines of PHP, it takes a few hundred lines of code to store and manage the information about those links. The module needs to create a database table to store its records, provide management pages so an admin can add new links, manage permissions, handle adding and editing records, request confirmation when administrators delete a record, and so on.

Drupal has a lot of forms to fill out and not all of them may be just the way you want or need them to be. Modifying forms is a topic that is often met with groans but once you understand the two methods to accomplish the task and the basic, underlying concepts, it really isn't that hard to do at all. You'll be a form-modifying, input-customizing wiz in no time. This article will briefly discuss what's going on and then mainly focus on showing working examples for both methods in Drupal 5 and 6. You should be comfortable creating a new function, looking at arrays and a having at least a passing understanding of the Forms API is real handy. Also note that in the examples below I have them wrapped in php tags but you should not include those if you copy/paste. That is just so it looks nice and clear for the article.

Deciding to make the change in the theme or a module

So there are two methods for altering form output in Drupal, one at the theme layer and the other through a custom module. Changes to the HTML can be accomplished with either method so most people will use the method they are more comfortable with already; themers use the theme and developers use a module. There are two situations however where you will want to use a module rather than a theme:

1. Changing functionality of a form (e.g. adding new validation rules or submission actions) can only happen in a module.

During a recent Lullboat podcast we mentioned a new feature in Drupal 6 that allows you replace any string in Drupal without using Locale module (thanks Moshe!). Faithful podcast listener Rob Loach took it upon himself to write the String Overrides module that lets you accomplish this task with ease in Drupal 6.

While Lullabots were lamenting the fact that this feature was never in Drupal 5, we realized that it actually could be accomplished. An hour after undertaking the project, the patch was submitted to the String Overrides queue and committed shortly afterwards.

String Overrides accomplishes this in Drupal 5 by imitating the Locale module, and without hitting the database (since variables are cached and pulled up on every request anyway). Since this essentially a hack for Drupal 5, you cannot combine it with Locale module or languages other than English. Here's the key code that makes this possible: