Custom Validation while adding a term under taxonomy

Question

I want to use custom validation while adding a term. I used form alter and #validate function it's not working.Default validation function under taxonomy module is working but my custom validate function is not.

Here is my code

  function lms2_validate_form_alter($form , &$form_state, $form_id){

    if ($form_id == 'taxonomy_form_term'){          
      $form['#validate'][] = 'lms2_validate_term_validate';
    }
  } 

  function lms2_validate_term_validate($form ,&$form_state){
      drupal_set_message('hello');
  }  

Answer 1

This would solve your problem for sure. However I would recommend you to have a look at hook_form_FORM_ID_alter

It is recommended to use hook_form_FORM_ID_alter if your module is implementing the hook only for a couple of forms or so. It gives better performance as it is being invoked only for the particular form and not for all and then checking it in if/else or switch/case loop.

Example: Considering your module name is: lms2_validate

function lms2_validate_taxonomy_form_term_alter(&$form, &$form_state, $form_id) {
 $form['#validate'][] = 'lms2_validate_term_validate';
}

function lms2_validate_term_validate($form, &$form_state) {
 drupal_set_message('hello');
}

NOTE: There is no if/else loop needed.

Answer 2

In Drupal 7, if you go through hook_form_alter.

It uses $form as a reference. You need to use & before $form.

/**
 * Implements hook_form_alter
 */
function hook_form_alter(&$form, &$form_state, $form_id) {
  switch ($form_id) {
    case 'taxonomy_form_term': 
      $form['#validate'][] = 'mymodule_taxonomy_form_custom_validate';
      break;
  }
}
/**
 * Implements hook_form_validate
 */
function hook_taxonomy_form_custom_validate($form, &$form_state) {
  //validation goes here
}

Let say if your module name is lms2_validate then use:

function lms2_validate_form_alter(&$form, &$form_state, $form_id) {
  if ($form_id == 'taxonomy_form_term') {
    $form['#validate'][] = 'lms2_validate_term_validate';
  }
}

function lms2_validate_term_validate($form, &$form_state) {
  drupal_set_message('hello');
}