Question

If the hook is called hook_field_settings_form($field, $instance, $has_data), my module is called mymodule. How can I use this hook on my form?
I would guess mymodule_field_settings_form($field, $instance, $has_data). But it’s a address field (<div class="myformclass" id="myformid">) in a form. How can I apply this function to only my address field?

EDIT:
What I’m trying to achieve here is the following thing. I have a create content page and in this page, you can fill in an address. I want to make some field of this address required and some are not required. So I figured out, I need the hook_field_settings_form-hook… Right?

Answer 1

you can use hook_form_alter

I used this myself to make the title field not required as I did not want it to be visible.
Important to use the if statement otherwise it will try to alter every form that you load. I am not sure what drupal version you have but this is drupal 7 even though other versions are pretty similar.

/**
 * 
 * Form Alter Widget
 * 
 */
 function mymodule_form_alter(&$form, &$form_state, $form_id) {
  if($form_id == 'myformid') {
    $form['title']['#required'] = false;
  }
}