You are here

Drupal Hooks and Functions I Can't Live Without

published by Diego F. Roldán on Thu, 01/13/2011 - 15:55

Hooks

hook_menu I use the hook menu to provide REST calls for custom application APIs, as well as to handle AJAX requests which may or may not need a response. I typically use it to respond with a JSON object to validate the request or to simply return custom data values.

hook_theme D6/7 This hook is awesome for creating custom templates, specially when creating custom modules in which you would like to provide a custom template for its visual presentation. Expand

<?php
/**
 * Implementation of hook_theme().
 */
function arts_theme($existing, $type, $theme, $path) {
  $path = drupal_get_path('module', 'arts');
  // Each parent key on this array will define and register a theme.
  return array(
    'arts_gallery_item' => array(
      'variables' => array('imagesrc' => NULL),
      'template' => 'arts_gallery_item', // this is the name of the template without the suffix .tpl.php
      'path' => $path . '/templates', // I usually create a template folder in custom modules to store the tpls.
    ),
  );
}
?>

This preprocess is optional and is solely intended to modify or add variables in $vars. Any module can override these variables by simply defining their own hook_preprocess_arts_gallery_item.

<?php
/**
 * Implementation of hook_preprocess_arts_gallery_item().
 */
function arts_proprocess_arts_gallery_item(&$vars) {
  // Let's modify the imagesrc variable, e.g. logo.gif.
  $vars['imagesrc'] = 'sites/all/files/images/arts.gif';
  // In addition, I can add new variables.
  $vars['path'] = drupal_get_path('theme', 'roldanarts');
}
?>

And to invoke the newly created theme, simply use

<?php
print theme('arts_gallery_item', 'logo.gif');
?>

hook_views_query_alter Love this hook for altering Views queries, specially in the case when I need to perform unsupported operations. For instance, here's how I used this hook to be able to add the OR operation for the WHERE Clause since Views 6.x-2.11 automatically performs and AND operation. Expand

Say for instance I wanted to have the following WHERE clause on a View called "featured_arts".

<?php
db_query('SELECT n.title FROM {node} n WHERE n.type = "%s" AND (n.resource_type = "%s" OR n.featured = "%s")', 'featured', 'community', 'frontpage');
?>

Through the Views UI, I wouldn't have been able to add that (OR) operation, but it can easily be achieved thru the hook, like this

<?php
/**
 * Implementation of hook_views_query_alter().
 */
function hook_views_query_alter(&$view, &$query) {
  switch($view->name) {
    case 'featured_arts':
      $view->query->add_where('featured_arts_filter', '(node.resource_type = "%s" OR node.featured = "%s")', 'community', 'frontpage');
      break;
  }
}
?>

Worth noting: The first argument in the add_where function, in this example "featured_arts_filter", refers to whether this additional WHERE clause should be treated as a new AND/OR section.

hook_init When building custom modules, this is the hook for adding JS and CSS files. Expand

<?php
/**
 * Implementation of hook_init().
 */
function arts_init() {
  $path = drupal_get_path('module', 'arts');
  drupal_add_css($path . '/css/arts.css');
  drupal_add_js($path . '/js/arts.js');
}
?>

Functions

db_rewrite_sql() When creating and executing custom queries, this function will add access control checks against the SQL query. Very helpful, for filtering content based on permissions granted to different roles.

* This blog gets modify constantly since I use it all the time for my own reference.

Overrides

themehook_links When theming menus this is perfect to override the default markup. For instance, here's the function signature if I wanted to override the System Main Menu. Expand

lifestyle:

medium:

tags: