Drupal 7 form alter required field is not working when i used field from "Add existing field"

Question

I have added two fields in to my custom content type using "Add existing field".

For specific URL, I need to set these two fields as Required.

So I have altered my form and set required condition. After setting it, I have printed the form using devel, these fields are having required settings.

$form['field_name']['und']['#required'] = TRUE;
$form['field_email']['und']['#required'] = 1;
dsm($form);

But required condition is not applied.

That is, I could not see red color required indication as well as its not working in the form submit.

Answer 1

Try

$form['field_email']['und']['0']['value']['#required'] = TRUE;

and if not work then try

$form['field_email']['und']['0']['#required'] = TRUE;

Answer 2

I ended up needing an additional value set to make this work and thoguht others might benefit from knowing so:

$form['profile_personal_information']['field_company'][LANGUAGE_NONE]['#required'] = 1;
$form['profile_personal_information']['field_company'][LANGUAGE_NONE][0]['#required'] = TRUE;
$form['profile_personal_information']['field_company'][LANGUAGE_NONE][0]['value']['#required'] = TRUE;

Answer 3

You can use Field Validation module:

This module adds an extra tab to each field instance, allowing you to specify validation rules for your field instances.

Or use hook_field_validate in you custom module.