Checking whether a user has a specific role...

Drupal 6 makes it easy to check whether or not a user has a specific Access Privilege.  It is indeed used in most modules, as it is essential and yields much power and flexibility in use.

What Drupal 6 does however NOT make trivial, is to check whether or not a user has specific role ( a named role, e.g. "administrator", "authenticated", "member" - whatever roles you may use).
How-to

<?php  global $user;

  // Check to see if $user has the administrator role.
  if (in_array('administrator', array_values($user->roles))) {
    // Do something.
  }?>

Here we use the default full array that each user has as an attribute - the collected roles of the user!  Note that this array is keyed, and the role names (not unique!) are thus kept in the values of the keyed array!
Why is this useful?
Well, let's suppose that you have a list of nodes (a blog-style for example), and these nodes in the listing are authored by different users - different users with different roles indeed!  Using the technique above, will enable you to theme the blog-entries of each user-role, making it easier to visually tell them apart on-page for the reader of the blog.

Drupal - How does it work...And how do I make it work for me?

Jeff Eaton presents Drupal to the developer.  He outlines the process of making a web-request, using index.php-controller as the stepping-stone, and how to hook into the Drupal-system.  "Hooking" is Drupals way of modifying functionality, and hooks are primarily implemented inside Modules.

Jeff does an amazing job of keeping it simple to understand, and reveals the processes that power Drupal enough to get you more than started coding your own Drupal Modules.

Node: Body outputs entire full node, instead of Body field

The problem is not, as the linked article here suggests, limited to Views representations of Node-body content.  The problem exists in any Node or Page template that is rendered to your website.

The problem arises from the fact that templating BOTH loads a Node, and then runs the "node-alter" routine on it - affecting the Node Body field specifically, to also include contents of CCK fields in that Node.

The problem-code
The problem arises when using this variable-call in a page-template (*.tpl.php) file:
print $node->body;
The solution-code
The solution is to replace the code above with this code instead:
print $node->content['body']['#value'];

CCK - Compound Fields - Image + Rich Text Caption + Taxonomy...

Here is a great article, outlining how to create your very own compound fields for use in CCK. The article EVEN (!!!) supplies you with two concrete implementations of modules, as added bonus...
- Image + Rich Text Caption + Taxonomy
- Modified User-page fields

You may download these two modules from the bottom of the same page, as linked to above...

Themes per content-type, and not only per node ID

This addresses the issue of ONLY having the possibility of theming nodes per node-ID, e.g:
"page-node-101.tpl-php"

In order to overcome this, and provide theming for each content-type (Defaults are of course "page", "story" in Drupal 6) that you may have created using CCK, you should look to modifying the code of the "theme_preprocess_page" function in your main "template.php"-file of your chosen theme.

Code to include in theme_preprocess_page
Here is the code to include...

// Add per content type pages
if (isset($vars['node'])) {
// Add template naming suggestion. It should alway use hyphens.
// If node type is "custom_news", it will pickup "page-custom-news.tpl.php".
if($vars['node']) $prefixName="page-node-";
else $prefixName="page-";
$vars['template_files'][] = $prefixName. str_replace('_', '-', $vars['node']->type);
}

And, as you will see, it gives you access to using two new template-names for your content-type:
- For views etc. node-listings: page-CONTENTTYPE.tpl.php
- For node-details views: page-node-CONTENTTYPE.tpl.php

Developer documentation and examples...

The general Drupal API can be found at api.drupal.org

In addition to this, you will also benefit from some select free screencasts - These display real-world usage of Drupal and Modules to provide certain custom page and content views. I can personally recommend these two...

• Drupal Videos
• Drupal School

Both of the above are accessible through iTunes and the iTunes Store...

Additionally, you might also like to have a copy of one or all of the Drupal Cheat Sheets lying around - It tells you all about the default variables, such as the login-status of your visiting user, and such essentials...