Objective

Make whatever we want before validate and submit a node.

Objective

Create a custom module with a form to set/get custom system variables from Drupal. We're going to add custom permissions to access this new page. Bonus: add simple page to count every node for each content type.

Summary

• Step 1: create custom module
• Step 2: call hook_menu and hook_permissions
• Step 3: create custom callbacks for new menus
• Step 4: create a Drupal form by code. Form, validate and submit

If there is something that makes great CMS like Drupal in these days is, undoubtedly, the number of modules or plugins availables, whether made by the community or by professionals who try to live with it. 

Focusing on Drupal extensions, the quantity of modules currently available is huge, more than 18000. Therefore, it's good to have a guide to those who are essential to almost any web project.

Mandatory list of modules for any Drupal website