Drupal image attach block module

Written at 17:28, on Friday 14 September 2007. Tags: drupal .

I recently created several PHP blocks for a Drupal website that made heavy use of the image module and the image_attach module. While the block creation wasn’t very difficult, it was still a process that took me a long night of researching api.drupal.org and fiddling with SQL queries. (It was a great exercise though, since I hadn’t practiced my PHP/MySQL skills since I followed a basic course at C-MD last spring. It’s amazing how much you forget if you don’t keep practicing… )

Anyway, the website I created these blocks for has an extensive product database set-up as custom nodes in Drupal. Besides presenting plain text information on their products, they also wanted to easily maintain their product photo’s, and present them in galleries. To make this possible, I set up the image module. All photographs were imported at once via FTP, and attached to individual product nodes through the image_attach module. This proved to be very useful, since they could attach the same image to various products, e.g. for variants of the same product, and also multiple images to one product.

The challenge was for product pages to display the images in the sidebar. In Drupal, there is a clear seperation between node content and all other content, and they don’t mix very well. So it’s very difficult to display a piece of content in another place on your website without resorting to hacks or writing checks in your theme display logic. After Googling for a while, I took it upon myself to write two PHP blocks: one that displayed the attached images to the currently viewed node, and one block that displayed the nodes attached to the currently viewed image. This established the relationship between image and product, and allows users to click through the photo album to products, and vice versa.

Setting up these blocks wasn’t particularly hard with the great example of the hook_block function provided with the Drupal API documentation. With this template, it was mostly a matter of copying the provided code, and filling in the blanks for displaying my own queries. I spent a lot of time investigating Drupal’s query functions, and searching for ways to access node information in a block context. For that, the following snippet proved very handy:

<?php 
if (arg(0) == 'node' && is_numeric(arg(1))) {
  $node = node_load(arg(1));
  // Rest of the code here...
}; ?>

This loads the node object, the concept in Drupal for a content page (as opposed to dynamically generated pages, such as listings of pages). Knowing what piece of content a user is currently viewing is essential for determining if the block needs to do something with it.

While the PHP blocks work great, I decided to go the extra mile and create modules of them. This has numerous advantages. By creating a module, the functionality can be easily deployed on other Drupal installations. For this customer, several localized product databases will be set-up. In a multi-site setup, this will mean that the codebase can be maintained and updated from one codebase. Also, the block can then have it’s own theming, instead of the generic block theming. And it’s possible to define addtional defaults or configuration settings.

I’m sure there are lots of improvements that could be made to this module (and I’d love to hear about them!), but it’s quite usable based on my own tests. I’m not sure if it should have a long live, since it would be perfectly acceptable for the Image module maintainers to integrate this in their own module. Nevertheless, I’ve attached the current code for you to download. Please leave a message if you find it useful, or if you have any suggestions for improvements!

Update: the code is now included in the Image module, thus obseleting this module!