hook_block

Definition

hook_block($op = 'list', $delta = 0, $edit = array())
developer/hooks/core.php, line 158

Description

Declare a block or set of blocks.

Any module can export a block (or blocks) to be displayed by defining the _block hook. This hook is called by theme.inc to display a block, and also by block.module to procure the list of available blocks.

The functions mymodule_display_block_1 and 2, as used in the example, should of course be defined somewhere in your module and return the content you want to display to your users. If the "content" element is empty, no block will be displayed even if "subject" is present.

After completing your blocks, do not forget to enable them in the block admin menu.

For a detailed usage example, see block_example.module.

Parameters

$op What kind of information to retrieve about the block or blocks. Possible values:

'list': A list of all blocks defined by the module.
'configure': A configuration form.
'save': Save the configuration options.
'view': Information about a particular block and default settings.

$delta Which block to return (not applicable if $op is 'list'). Although it is most commonly an integer starting at 0, this is not mandatory. For instance, aggregator.module uses string values for $delta

$edit If $op is 'save', the submitted form data from the configuration form.

Return value

If $op is 'list': An array of block descriptions. Each block description is an associative array, with the following key-value pairs:
- 'info': (required) The human-readable name of the block.
- 'cache': A bitmask of flags describing how the block should behave with respect to block caching. The following shortcut bitmasks are provided as constants in block.module:
  - BLOCK_CACHE_PER_ROLE (default): The block can change depending on the roles the user viewing the page belongs to.
  - BLOCK_CACHE_PER_USER: The block can change depending on the user viewing the page. This setting can be resource-consuming for sites with large number of users, and should only be used when BLOCK_CACHE_PER_ROLE is not sufficient.
  - BLOCK_CACHE_PER_PAGE: The block can change depending on the page being viewed.
  - BLOCK_CACHE_GLOBAL: The block is the same for every user on every page where it is visible.
  - BLOCK_NO_CACHE: The block should not get cached.
- 'weight', 'status', 'region', 'visibility', 'pages': You can give your blocks an explicit weight, enable them, limit them to given pages, etc. These settings will be registered when the block is first loaded at admin/block, and from there can be changed manually via block administration. Note that if you set a region that isn't available in a given theme, the block will be registered instead to that theme's default region (the first item in the _regions array).
- If $op is 'configure': optionally return the configuration form.
- If $op is 'save': return nothing.
- If $op is 'view': return an array which must define a 'subject' element and a 'content' element defining the block indexed by $delta.

Name	Description
Hooks	Allow modules to interact with the Drupal core.

Code

<?php
function hook_block($op = 'list', $delta = 0, $edit = array()) {
  if ($op == 'list') {
    $blocks[0] = array('info' => t('Mymodule block #1 shows ...'),
      'weight' => 0, 'status' => 1, 'region' => 'left');
      // BLOCK_CACHE_PER_ROLE will be assumed for block 0.

    $blocks[1] = array('info' => t('Mymodule block #2 describes ...'),
      'cache' => BLOCK_CACHE_PER_ROLE | BLOCK_CACHE_PER_PAGE);

    return $blocks;
  }
  else if ($op == 'configure' && $delta == 0) {
    $form['items'] = array(
      '#type' => 'select',
      '#title' => t('Number of items'),
      '#default_value' => variable_get('mymodule_block_items', 0),
      '#options' => array('1', '2', '3'),
    );
    return $form;
  }
  else if ($op == 'save' && $delta == 0) {
    variable_set('mymodule_block_items', $edit['items']);
  }
  else if ($op == 'view') {
    switch($delta) {
      case 0:
        $block = array('subject' => t('Title of block #1'),
          'content' => mymodule_display_block_1());
        break;
      case 1:
        $block = array('subject' => t('Title of block #2'),
          'content' => mymodule_display_block_2());
        break;
    }
    return $block;
  }
}
?>