Module development - Drupal 7

Remarks#

Examples for developers module should be used as a reference for module development ideally. It has explanation of all the major APIs, well documented usage. It is all in for begineers to understand module development.

Basic module providing a simple page

really_neat.info

name = Really Neat Module
description = Provides a really neat page for your site
core = 7.x

really_neat.module

<?php

/**
 * @file
 * Hook implementation and shared functions for the Really Neat Module.
 */

/**
 * Implements hook_menu().
 */
function really_neat_menu() {
  $items = array();
  
  $items ['really/neat'] = array(
      'title' => 'A Really Neat Page',
      'page_callback' => 'really_neat_page',
      'access_callback' => TRUE, //Anyone can access. 
      // Or replace with array([name-of-permission]),
    ),

  return $items;
}

/**
 * Page callback: Displays something really neat
 */
function really_neat_page() {
  return "Really Neat!"
}

Basic module providing a custom block

custom_module.info

name = Custom Module
description = Creates a block containing a custom output.
core = 7.x

custom_module.module

/**
 * Initiates hook_block_info.
 *
 * Registers the block with Drupal.
 */
function custom_module_block_info() {
  $blocks = array();
    //Registers the machine name of the block.
  $blocks['custom_block'] = array(
      //Sets the human readable, administration name.
    'info' => t('My Custom Block'),
      //Tells Drupal not to cache this block.
      //Used if there is dynamic content.
    'cache' => DRUPAL_NO_CACHE,
  );
  return $blocks;
}

/**
 * Initiates hook_block_view().
 *
 * Sets the block title and content callback.
 */
function custom_module_block_view($delta = '') {
  $block = array();

  switch ($delta) {
      //Must be the machine name defined in the hook_block_info.
    case 'custom_block':
        //The blocks title.
      $block['subject'] = 'My custom block';
        //The string or function that will provide the content of the block.
      $block['content'] = custom_module_block_content(); 
      break;
  }

  return $block;
}

/**
 * Returns the content of the custom block.
 */
function custom_module_block_content() {
  $content = "This function only returns a string, but could do anything."

  return $content;
}

Basic custom form for inclusion in either page or block examples.

Simple form, validation and submission functions to create a “mailing list” feature. This can then be applied to either the basic page or basic block examples.

Assumes you have created a table in the drupal database called ‘mailing_list’ with the fields first name, last name and email address.

Additional information on the Form API and additional field options: https://api.drupal.org/api/drupal/developer!topics!forms_api_reference.html/7.x/

function custom_module_form($form, &$form_state) {
  $form['first_name'] = array (
    '#type' => 'textfield',
    '#title' => 'First Name',
    '#required' => TRUE,
  );
  $form['last_name'] = array (
    '#type' => 'textfield',
    '#title' => 'Last Name',
    '#required' => TRUE,
  );
  $form['email'] = array (
    '#type' => 'textfield',
    '#title' => 'First Name',
    '#required' => TRUE,
  );

  return $form;
}

function custom_module_form_validate($form, &$form_state) {
  if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
    form_set_error('email', t('Please provide a valid email address.'));
  }
}

function custom_module_form_submit($form, &$form_state) {
  //Useful function for just getting the submitted form values
  form_state_values_clean($form_state);

  //Save time later by assigning the form values to variables.
  $first_name = $form_state['values']['first_name'];
  $last_name = $form_state['values']['last_name'];
  $email = $form_state['values']['email'];

  //Insert the submitted data to the mailing_list database table.
  db_insert('mailing_list')
    ->fields(array(
      'first name' => $first_name,
      'last name' => $last_name,
      'email' => $email,
    ))
    ->execute();
  //Set a thank you message.
  drupal_set_message('Thank you for subscribing to our mailing list!');

  //drupal_goto() could be used here to redirect to another page or omitted to reload the same page.
  //If used, drupal_goto() must come AFTER drupal_set_message() for the message to be displayed on the new page.
}

Basic module providing a custom block

custom_module.info

name = Custom Module
description = Creates a block containing a custom output.
core = 7.x

custom_module.module

/**
 * Initiates hook_block_info.
 *
 * Registers the block with Drupal.
 */
function custom_module_block_info() {
  $blocks = array();
    //Registers the machine name of the block.
  $blocks['custom_block'] = array(
      //Sets the human readable, administration name.
    'info' => t('Titania Price Widget'),
      //Tells Drupal not to cache this block.
      //Used if there is dynamic content.
    'cache' => DRUPAL_NO_CACHE,
  );
  return $blocks;
}

/**
 * Initiates hook_block_view().
 *
 * Sets the block title and content callback.
 */
function custom_module_block_view($delta = '') {
  $block = array();

  switch ($delta) {
      //Must be the machine name defined in the hook_block_info.
    case 'custom_block':
        //The blocks title.
      $block['subject'] = 'My custom block';
        //The string or function that will provide the content of the block.
      $block['content'] = custom_module_block_content(); 
      break;
  }

  return $block;
}

/**
 * Returns the content of the custom block.
 */
function custom_module_block_content() {
  $content = "This function only returns a string, but could do anything."

  return $content;
}

Basic custom form for inclusion in either page or block examples.

Simple form, validation and submission functions to create a “mailing list” feature. This can then be applied to either the basic page or basic block examples.

Assumes you have created a table in the drupal database called ‘mailing_list’ with the fields first name, last name and email address.

Additional information on the Form API and additional field options: https://api.drupal.org/api/drupal/developer!topics!forms_api_reference.html/7.x/

function custom_module_form($form, &$form_state) {
  $form['first_name'] = array (
    '#type' => 'textfield',
    '#title' => 'First Name',
    '#required' => TRUE,
  );
  $form['last_name'] = array (
    '#type' => 'textfield',
    '#title' => 'Last Name',
    '#required' => TRUE,
  );
  $form['email'] = array (
    '#type' => 'textfield',
    '#title' => 'First Name',
    '#required' => TRUE,
  );

  return $form;
}

function custom_module_form_validate($form, &$form_state) {
  if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
    form_set_error('email', t('Please provide a valid email address.'));
  }
}

function custom_module_form_submit($form, &$form_state) {
  //Useful function for just getting the submitted form values
  form_state_values_clean($form_state);

  //Save time later by assigning the form values to variables.
  $first_name = $form_state['values']['first_name'];
  $last_name = $form_state['values']['last_name'];
  $email = $form_state['values']['email'];

  //Insert the submitted data to the mailing_list database table.
  db_insert('mailing_list')
    ->fields(array(
      'first name' => $first_name,
      'last name' => $last_name,
      'email' => $email,
    ))
    ->execute();
  //Set a thank you message.
  drupal_set_message('Thank you for subscribing to our mailing list!');

  //drupal_goto() could be used here to redirect to another page or omitted to reload the same page.
  //If used, drupal_goto() must come AFTER drupal_set_message() for the message to be displayed on the new page.
}

Example custom_module.install file for creating a database table

Can be used in conjunction with the custom form example to create a table in the drupal database for a Mailing List feature.

This example was made by creating the table directly in my development database, then created the data for hook_schema() using the Schema module.

This allows for automatic table creation during module install on staging and production sites.

custom_module.install

/**
 * Installs the database schema.
 */
function custom_module_install() {
  drupal_install_schema('mailing_list');
}

/**
 * Uninstalls the database schema.
 */
function custom_module_uninstall() {
  drupal_uninstall_schema('mailing_list');
}

/**
* Creates the tables using the schema API.
*/
function custom_module_schema() {
  $schema['mailing_list'] = array(
    'description' => 'TODO: please describe this table!',
    'fields' => array(
      'first name' => array(
        'description' => 'TODO: please describe this field!',
        'type' => 'int',
        'not null' => TRUE,
      ),
      'last name' => array(
        'description' => 'TODO: please describe this field!',
        'type' => 'int',
        'not null' => TRUE,
      ),
      'email' => array(
        'description' => 'TODO: please describe this field!',
        'type' => 'int',
        'not null' => TRUE,
      ),
    ),
  );
}