1. 4.6.x developer/examples/block_example.module
  2. 4.7.x developer/examples/block_example.module
  3. 5.x developer/examples/block_example.module

This is an example outlining how a module can be used to define a block to be displayed on the right or left side of each page.

File

developer/examples/block_example.module
View source
<?php

/**
 * @file
 * This is an example outlining how a module can be used to define a block
 * to be displayed on the right or left side of each page.
 */

/**
 * Implementation of hook_help().
 *
 * Throughout Drupal, hook_help() is used to display help text at the top of
 * pages. Some other parts of Drupal pages get explanatory text from these hooks
 * as well. We use it here to provide a description of the module on the
 * module administration page.
 */
function block_example_help($section) {
  switch ($section) {
    case 'admin/modules#description':

      // This description is shown in the listing at admin/modules.
      return t('An example module showing how to define a block.');
  }
}

/**
 * Implementation of hook_block().
 *
 * This hook both declares to Drupal what blocks are provided by the module, and
 * generates the contents of the blocks themselves.
 */
function block_example_block($op = 'list', $delta = 0) {

  // The $op parameter determines what piece of information is being requested.
  if ($op == 'list') {

    // If $op is "list", we just need to return a list of block descriptions. This
    // is used to provide a list of possible blocks to the administrator.
    $blocks[0]['info'] = t('A simple text string');
    $blocks[1]['info'] = t('An empty block');
    return $blocks;
  }
  else {
    if ($op == 'view') {

      // If $op is "view", then we need to generate the block for display purposes.
      // The $delta parameter tells us which block is being requested.
      switch ($delta) {
        case 0:

          // The subject is displayed at the top of the block. Note that it should
          // be passed through t() for translation.
          $block['subject'] = t('Title of block #1');

          // The content of the block is typically generated by calling a custom
          // function.
          $block['content'] = block_example_contents(1);
          break;
        case 1:
          $block['subject'] = t('Title of block #2');
          $block['content'] = block_example_contents(2);
          break;
      }
      return $block;
    }
  }
}

/**
 * A block content function.
 */
function block_example_contents($which_block) {
  if ($which_block == 1) {

    // Modules would typically perform some database queries to fetch the content
    // for their blocks. Here, we just return a string.
    return t('Some example content.');
  }
  if ($which_block == 2) {

    // It is possible that your block will not have any content, since it is
    // probably dynamically constructed. In this case, Drupal will not display
    // the block at all.
    return;
  }
}

Functions

Namesort descending Description
block_example_block Implementation of hook_block().
block_example_contents A block content function.
block_example_help Implementation of hook_help().