Trim or strip spaces around the email or username on the login page [closed]

Question

I know that my Drupal installation (9.3.15) doesn't trim spaces at the login page (form id: user-login-form). I have some code in the HOOK_form_user_login_form_alter but in that place in $form_state I don't have any ->getValue('%field%') , it returns NULL. Also I can not modify '$form['name']['#value']' because it is empty in that context.

How do I trim spaces on the user's input? I can do $form_state->getUserInput(); and I can see what the user has entered but I don't know how to modify it. Because $form_alter is an object.

Answer 1

In your_module.module

1. You create form alter if there is no any (e.g. HOOK_form_FORM_ID_alter())
2. you add a validation callback to a field of the whole form (e.g. array_unshift($form['#validate'], 'trim_login_credentials');)
3. create function trim_login_credentials(&$form, $form_state) {}
4. add your validation or string operations into that the newly created function;

I do 'array_unshift()` because I want my validation before Drupal's.

Another way

A question at stackoverflow