Creation of Hello World module in Drupal 6

1. Create a folder for your module

Create a folder in your modules directory called helloworld ie sites/all/modules/helloworld/. It is good practice to put all custom modules in sites/all/modules/ folder and not the modules/ folder. The modulesfolder is meant for core modules any “third party” or custom modules should be in sites/all/modules/.

So now that you’ve created the folder sites/all/modules/helloworld/

2. Create the *.info file

Create a file called modulename.info in this case helloworld.info

?

1 2 3 4

; $Id$ name = Hello World Module description = My very first Drupal Module core = 6.x

This lets Drupal know about your module

3. Create the *.module file

Create a file called modulename.module in this case helloworld.module

We need to let Drupal know what path the module will be accessible from. We do this by using thehook_menu() hook. To implement  hooks follow the following convention: modulename_hookname(). So for our module we must create a function called helloworld_menu(). More info here .

?

1 2 3 4 5 6 7 8 9 10 11

function helloworld_menu(){ $items = array(); $items['helloworld'] = array( 'title' => t('Welcome to the Hello World Module'), 'page callback' => 'helloworld_page', 'page arguments' => array(1), 'access arguments' => array('access content'), 'type' => MENU_CALLBACK,   );   return $items; }

Break Down

We created $items['helloworld'] array item. This lets drupal know about the path we want to use for our module.

title: this is what gets printed at the top of the page. The page title.
page callback: This is the function that gets called when the url is accesed.
page arguments: must be array of arguments that get parsed to the call back function, not required.
access arguments: array of access permissions in this case any role with ‘access content’ permissions can access the page.
type: specifies the menu type check hook_menu()  for more details the Drupal hook.

So in a nutshell, when Drupal hits the http://mysite.com/helloworld url it will look for a call back function called helloworld_page(). Simple Enough. Now lets create the helloworld_page() function.

?

1 2 3

function helloworld_page($argument) {    return "Hello World!"; }

So your helloworld.module file will contain:

?

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

<?php function helloworld_menu(){ $items = array(); $items['helloworld'] = array( 'title' => t('Welcome to the Hello World Module'), 'page callback' => 'helloworld_page', 'page arguments' => array(1), 'access arguments' => array('access content'), 'type' => MENU_CALLBACK,   );   return $items; } function helloworld_page($argument) {     return "Hello World! Arguments parsed was " . $argument; }

How to easily create a custom module for Drupal 6?

Let's break this down into a few easy steps.

1. Know where custom modules go, not in /modules but in /sites/all/modules
2. Create a new folder there, e.g., new.
3. Open a text editor and create a file named new.info
4. In new.info add the following lines:
   
   ; $Id
   name = New
   description = A new module for testing
   package = Other
   core = 6.x
5. Create another file named new.module
6. In new.module add the following lines:
   <?php
/**
* Implementation of hook_block().
* Adds a block that has new text.
*/
function new_block($op = 'list', $delta = 0, $edit = array()) {
  switch ($op) {
    case 'list':
      $blocks[0]['info'] = t('New Module');
      return $blocks;
    case 'view':
      $block[0]['subject'] = t('New Module');
      $block[0]['content'] = t('Hi from your custom block and your first new module');
       return $block[$delta];
  }
}
7. Make sure both files are saved and then in Drupal go to Site Building -> Modules. Look under the other category and you should see your new module listed. Just check the box for it and submit.
8. You now have a new module which creates a custom block, you can go to Site Building -> Blocks and you should see your new module block. You can select to enable it and add it your pages. 
9. The possibilities with modules are nearly endless, I recommend you pick up Pro Drupal Development  for more instructions.