[SOLVED][Drupal Webform] How to add custom validation/submit code to a Webform?

• Use the following code in one of your custom modules or create one specifically for this purpose
  

  <?php
  /**
   * Implementation of hook_form_alter().
   */
  function mywebform_extra_form_alter(&$form, &$form_state, $form_id) {
    // Add validation for a particular Webform node:
    if ($form_id == 'webform_client_form_21') {
      // Simply add the additional validate handler.
      $form['#validate'][] = 'mywebform_extra_validate_21';
  
      // Add the submit handler after the existing Webform submit handler,
      // but before the second Webform handler. Pop off the first one and add
      // ours second.
      $first = array_shift($form['#submit']);
      array_unshift($form['#submit'], $first, 'mywebform_extra_submit_21');
    }
  }
  
  /**
   * Validation handler for Webform ID #21.
   */
  function mywebform_extra_validate_21(&$form, &$form_state) {
    global $user;
    if (!isset($user->roles[4])) {
      form_set_error('', t('Your user role is not allowed to submit this Webform.'));
    }
  }
  
  /**
   * Submit handler for Webform ID #21.
   */
  function mywebform_extra_submit_21(&$form, &$form_state) {
    global $user;
  
    // Changes can be made to the Webform node settings by modifying this variable:
    $form['#node']->webform;
  
    // Insert things into other database tables or modify properties.
  }
  ?>

• Just remember that "webform_client_form_21" is an example id of the id of the webform. Replace it with the id of the webform you need to change.

Hope that helps.