Drupal form validation not working for me

Question

I am trying to modify some Drupal 6 form code and incorporate some native form validation. Code looks like this, but validation does not work. I never even get into function thisFormName_form_validate. Any Drupalians have some good ideas?

function thisFormName_form_alter(&$form, $form_state, $form_id) {
  $form['email_address'] = array(
    '#type' => 'textfield',
    '#title' => t('Enter your email address (optional)'),
    '#default_value' => $object['email_address'],
    '#weight' => 4,
    '#size' => 60,
    '#maxlength' => 128,  
    '#description' => t('Enter email address.'),
  );


function thisFormName_form_validate($node, &$form) {
  if ($form_state['values']['email_address'] == '') 
  {
    form_set_error('', t('Email must be valid format if entered.'));

  }
}

Answer 1

Since you are using form alter, so you don't create the form yourself, you should add the validation handler yourself:

function myModule_form_alter(&$form, $form_state, $form_id) {
  $form['email_address'] = array(
    '#type' => 'textfield',
    '#title' => t('Enter your email address (optional)'),
    '#default_value' => $object['email_address'],
    '#weight' => 4,
    '#size' => 60,
    '#maxlength' => 128,  
    '#description' => t('Enter email address.'),
  );
  $form['#validate'][] = 'my_validation_function';
}


function my_validation_function(&$form, &$form_state) {
  if ($form_state['values']['email_address'] == '') {
    form_set_error('', t('Email must be valid format if entered.'));
  }
}

Drupal will only by default use the validation that is defined as the form_name + _validate. This is not the case since you are using hook_form_alter.