Module Development

Altering Specific Forms and Customizing Validation for Drupal 7

Check your version

This tutorial covers a topic in Drupal 7 which may or may not be the version you're using. We're keeping this tutorial online as a courtesy to users of Drupal 7, but we consider it archived.

Alternate resources

Sprout Video

This video shows how to target a specific form with the hook_form_FORM_ID_alter and creating a customized validation function for a form.

Note: There is a typo in this video. (The code is correct in the downloadable example file attached to the previous video.)

In the demo_validate_password() function, the following line shown in the video if (in_array($form['values']['pass'], $badpasswords)) { should be if (in_array($form_state['values']['pass'], $badpasswords)) {.