Getting arguments from URL

Question

How do I get arguments from the URL? in other words, what is the equivalent of the arg() function of Drupal 7 and previous versions?

Answer 1

As reported in the arg() is deprecated and will be removed change record, the Drupal 8 (procedural) equivalent of arg() is the following one.

$current_path = \Drupal::service('path.current')->getPath();
$path_args = explode('/', $current_path);

As the change record makes notice, not all the times that is the correct code to use. Depending from the context, you should use code similar to the following one.

• Check if a path is for an administrative page

  if (\Drupal::service('router.admin_context')->isAdminRoute()) {
    // Your code.
  }
  

• Add CSS or JavaScript conditionally, basing on the page being visited

  function mymodule_page_attachments(array &$attachments) {
    if (\Drupal::routeMatch()->getRouteName() == 'my.route') {
      $attachments ['#attached']['library'][] = 'my_module/my_library'; // you'll need to define in mymodule.libraries.yml
    }
  }
  

• Load the currently viewed node

  $node = \Drupal::routeMatch()->getParameter('node');
  

Notice that in the first and last case, in Drupal 7 you should not use arg(), but respectively path_is_admin() and menu_get_object(). The typical beginner-Drupal-developer error is using arg() also in those cases.

Answer 2

Please see https://www.drupal.org/node/2150267

Drupal 7

$query = $_GET['q']; // query string param
$myparam = $_POST['myparam']; // form param
$request_method = $_SERVER['REQUEST_METHOD']; // server variable
$mycookie = $_COOKIE['mycookie']; // cookie

In Drupal 8

$query = \Drupal::request()->query->get('q'); // query string param
$name = \Drupal::request()->request->get('name'); // form param
$request_method = \Drupal::request()->server->get('REQUEST_METHOD'); // server variable
$mycookie = \Drupal::request()->cookies->get('mycookie'); // cookie

Answer 3

arg() is deprecated in drupal 8, however we can get values like arg() function does in drupal 7 & 6 by mentioned

$path = \Drupal::request()->getpathInfo();
$arg  = explode('/',$path);
print_r($arg); exit(); 

The output would be parameters in url except basepath or (baseurl),

Array
(
   [0] => 
   [1] => node
   [2] => add
)