How do I limit the access basing on the user role?

Question

How do I use an access callback to limit the access basing on the user role?

For example, in my site I have the following roles:

1. Administrator
2. Authenticate User
3. Anonymous user
4. Teacher

I want to make a particular page available only to the users who have the Teacher role. How can I achieve this?

function form_test_menu() {
  $items['programme_reg'] = array(
    'title' => 'Approved Programmes Registration',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('form_test_form'),
    'access callback' => 'user_access', 
    'access arguments' => array('Teaching')
  ); 

  return $items;
}

My code is not working.

Answer 1

user_access function takes permission name as an argument you can not pass user role name to it.

Here is how you can achieve this:

function MYMODULE_menu() {
  $items = array();

  $items['programme_reg'] = array(
    'title' => 'Approved Programmes Registration',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('MYMODULE_form_test_form'),
    'access callback' => '_MYMODULE_check_user_role',
  ); 

  return $items;
}

function _MYMODULE_check_user_role() {
  $account = $GLOBALS['user'];

  // Assuming that RID 4 is Teacher.
  // You can also check for role name in $account->roles array.
  return (isset($account->roles[4]) ? TRUE : FALSE);
}

Assuming that user role Teacher has Role ID as 4, you can check and return TRUE/FALSE in your own custom access callback. You can also check using Role Name instead of Role ID, see here for more details.

Answer 2

You have to implement hook_permission

e.g.,

function MyModule_permission() {
  return array(
    'teaching' => array(
      'title' => t('Teaching my module'),
      'description' => t('Perform teaching tasks for my module.'),
    ),
  );
}
function form_test_menu() {
    $items['programme_reg'] = array(
        'title' => 'Approved Programmes Registration',
        'page callback' => 'drupal_get_form',
        'page arguments' => array('form_test_form'),
        'access callback' => 'user_access', 
        'access arguments' => array('teaching'),
    ); 
    return $items;
}

After that, you can give access from permission page to any role

Answer 3

The code is wrong because the access callback used (user_access()) accepts a user permission string as argument, not a role name. To check the role the currently logged in user has, you need your own access callback. I would rather user permissions, since this would permit me not to alter the code in my module, in the case I need to check for more roles.

If I were asked to check for roles, I would use the following code, which runs on Drupal 7.36 and higher.

function form_test_menu() {
  $items['programme_reg'] = array(
    'title' => 'Approved Programmes Registration',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('form_test_form'),
    'access callback' => 'form_test_check_role', 
    'access arguments' => array('Teaching')
  ); 

  return $items;
}

function form_test_check_role($role_name) {
  if ($role = user_role_load_by_name($role_name)) {
    return user_has_role($role->rid);
  }

  // The role doesn't exists; return FALSE as safe value.
  return FALSE;
}