Modifying links with hook_menu_links_discovered_alter()for Drupal 8 , 9 , 10 , and 11

Within the flexible architecture of Drupal, hooks offer a powerful way to alter or extend the behavior of existing functionalities. In this lesson, we'll explore how to use hook_menu_links_discovered_alter() to modify Drupal menu links dynamically, which is a valuable skill when building custom modules that interact smoothly with the Drupal ecosystem.

Understanding hook_menu_links_discovered_alter()

The hook_menu_links_discovered_alter() allows developers to alter menu links after they are defined in the system but before they are rendered. This is particularly useful when you need to adjust the properties of menu items, such as altering their titles, routes, or access permissions based on custom logic at runtime.

Implementing hook_menu_links_discovered_alter()

Let's walk through the steps to implement this hook in your custom module:

Step 1: Implement the Hook

To use this hook, you first need to define it in your module's .module file. Let's say your module is named my_rest_module. Add the following function in my_rest_module.module:

      
          /**
           * Implements hook_menu_links_discovered_alter().
           *
           * @param array $links
           *   An associative array of all menu links.
           */
          function my_rest_module_menu_links_discovered_alter(array &$links) {
            // Adjust the title of a link programmatically.
            if (isset($links['my_rest_module.admin'])) {
              $links['my_rest_module.admin']['title'] = t('Updated Admin Menu Title');
            }

            // Alter permissions for a link.
            if (isset($links['my_rest_module.content'])) {
              // Change the required permission for accessing this link.
              $links['my_rest_module.content']['options']['attributes']['title'] = t('Updated Content Management Link');
            }
          }
      
    

In this example:

• The title of the my_rest_module.admin link is altered to "Updated Admin Menu Title".
• Additional properties or attributes of the my_rest_module.content link can be altered to include an updated title attribute.

Step 2: Clear Cache

Whenever you change the module's code, especially in hooks, it is important to clear Drupal's cache to ensure your changes take effect:

      
          drush cr
      
    

This step is crucial for reflecting all alterations you make using hooks in the live menu.

Advanced Use Cases and Tips

While hooks allow basic modifications, advanced logic can dynamically control when and how menu links appear, move, or modify based on various factors.

Conditional Modifications

Dynamically adjust links based on user roles, current pages, or other state-based conditions:

      
          function my_rest_module_menu_links_discovered_alter(array &$links) {
            if (isset($links['my_rest_module.admin']) && \Drupal::currentUser()->hasPermission('special admin access')) {
              $links['my_rest_module.admin']['title'] = t('Special Admin Menu');
            }
          }
      
    

Here, the my_rest_module.admin title is adjusted only if the current user holds a specific permission.

Adding Dynamic Attributes

Sometimes you might need to add dynamic attributes to a menu link. You can do so by updating the link’s options:

      
          $links['example.link']['options'] = [
            'attributes' => [
              'data-example' => 'dynamic-data'
            ],
          ];
      
    

These small touches can help tailor user experiences to match dynamic content delivery or interaction insights.

Verifying Changes

Test the alterations by navigating to the menu locations in Drupal's UI to ensure that the hooks are applied correctly and achieving the desired effects. Consider using the devel module’s Kint, a powerful debugging tool, to inspect the menu link structure deeply.

Conclusion

By leveraging hook_menu_links_discovered_alter(), you can significantly enhance the adaptability and responsiveness of your Drupal site's navigation. This capability enables you to create an intuitive user experience that dynamically aligns with your module's logic and user needs, marking a critical component in professional Drupal development.

What’s Next?

Having mastered altering menu links, the next step is exploring Creating Custom Contextual Links to provide dynamic interactions based on content contexts, further elevating your module's interactivity and user engagement.