enter image description here

I have created content type with field as List(text). If I select any of above option and try to save it, it through "fieldName: illegal value" error.But if I modified option in below format and then try to save it. It get saved successfully.





Does list doesnot support first format? Is there any other way to resolve this without changing its format ?

  • Hi thanks for response. Yups its option group. Also attached image related to it. Commented Sep 14, 2016 at 9:36
  • here the problem is you havent provided the key properly . So its not able to store the value or get the value Commented Sep 14, 2016 at 9:38
  • Hi Shreya, so how should I provide key without changing format specified in image. Can you please help by giving any example. Commented Sep 14, 2016 at 10:09

1 Answer 1


You can achieve that by using hook_form_alter function.

I've tested the following code on my instance. It's working fine.

Use the following code in your custom module.

function YOUR_MODULE_form_alter(&$form, &$form_state, $form_id) {     
        if ($form['#form_id'] == 'YOUR-CONTENT-TYPE_node_form') {
         $form['YOUR-FILED-NAME']['und']['#options'] = array (
       'Group1' => array(
          1 => 'Option1',
          2 => 'Option2',

        'Group2' => array(
          3 => 'Option3',
          4 => 'Option4',
    return $form;

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