Add CSS class with hook

Question

I have a search box using custom_search module. I am trying to add multiple classes to the input field using a hook.

Here is the code I have tried:

<?php
function mytheme_form_search_block_form_alter(&$form, &$form_state) {
      $form['keys']['#attributes']['class'][] = 'custom_search-keys','form-search','form-control';
    }

But it does not add the classes to the search box input field?

Answer 1

Try this one, add class as array.

$form['keys']['#attributes'] = array('class' => array('custom_search-keys','form-search','form-control'));