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

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
)