best practice for email validation in form alter drupal 7

Question

What is the best recommended drupal way to validate an email is input on a new field I added in drupal settings page? Here is the code I have now:

function MYMODULE_form_uc_order_settings_form_alter(&$form, &$form_state, $form_id) {   $form['MYMODULE_uc_order_template_email'] = array(
'#title' => t('Template Email'),
'#default_value' => variable_get('MYMODULE_uc_order_template_email', '[email protected]'),
'#description' => t("Template Email"),
'#type' => 'textfield',
 );

}

Answer 1

The function valid_email_address($mail) in D7 validates any email passed into it. If you need to validate a new email field from a form altered form, you can add a validation handler to your newly add email field to ensure that it is valid. Just append to the $form['#validate'] array the function you want called for validation.

function MYMODULE_form_uc_order_settings_form_alter(&$form, &$form_state, $form_id)
  //@TODO: Other form modifications
  $form['#validate'][] = 'MYMODULE_form_uc_order_settings_form_validate';
}

Then in your form validation function, check the value of the submitted field with valid_email_address($mail).

function MYMODULE_form_uc_order_settings_form_validate($form, &$form_state) {
  if (!valid_email_address($form_state['values']['MYMODULE_uc_order_template_email'])) {
    form_set_error('MYMODULE_uc_order_template_email', 'Not a valid email address');
  }
}