Add a function to directly check if a user has access to a taxonomy term

src/AccessByTaxonomyService.php

@@ -9,7 +9,9 @@ use Drupal\Core\Entity\EntityFieldManagerInterface;
 use Drupal\Core\Entity\EntityStorageException;
 use Drupal\Core\Entity\EntityTypeManagerInterface;
 use Drupal\Core\Logger\LoggerChannelInterface;
+use Drupal\Core\Session\AccountInterface;
 use Drupal\field\Entity\FieldConfig;
+use Drupal\taxonomy\Entity\Term;
 
 /**
  * Class AccessByTaxonomyService.
@@ -26,6 +28,7 @@ final class AccessByTaxonomyService {
     private readonly EntityTypeManagerInterface $entityTypeManager,
     private readonly LoggerChannelInterface $loggerChannelAccessByTaxonomy,
     private readonly Connection $connection,
+    private readonly AccountInterface $account,
   ) {}
 
   /**
@@ -74,6 +77,65 @@ final class AccessByTaxonomyService {
     }
   }
 
+  /**
+   * Checks access to a term.
+   *
+   * @param int $tid
+   *   The taxonomy term ID to check for.
+   * @param \Drupal\Core\Session\AccountInterface|null $account
+   *   The optional account. If not passed, the current user is used.
+   *
+   * @return bool
+   *   Whether the user has access to the term.
+   */
+  public function canUserAccessTerm(int $tid, ?AccountInterface $account = NULL): bool {
+
+    // If the account is not passed, use the currently logged-in user.
+    if (!isset($account)) {
+      $account = $this->account;
+    }
+
+    $term = Term::load($tid);
+    if (!$term) {
+      return FALSE;
+    }
+    $allowed_roles = $term->get('field_allowed_roles')->getValue();
+    $result = TRUE;
+    if ($account->hasPermission('bypass node access')) {
+      return $result;
+    }
+    // In case the term has specified roles, check if the user has any of them.
+    if ($allowed_roles) {
+      $result = FALSE;
+      $user_roles = $account->getRoles();
+      $allowed_roles_simplified = [];
+      foreach ($allowed_roles as $role) {
+        $allowed_roles_simplified[] = $role['target_id'];
+      }
+      foreach ($user_roles as $role) {
+        if (in_array($role, $allowed_roles_simplified)) {
+          return TRUE;
+        }
+      }
+    }
+
+    // User has not been allowed by roles, check if in the allowed users list.
+    $allowed_users = $term->get('field_allowed_users')->getValue();
+    if ($allowed_users) {
+      $result = FALSE;
+      $allowed_users_simplified = [];
+      foreach ($allowed_users as $user) {
+        $allowed_users_simplified[] = $user['target_id'];
+      }
+      if (in_array($account->id(), $allowed_users_simplified)) {
+        $result = TRUE;
+      }
+    }
+
+    return $result;
+
+  }
+
   /**
    * Adds a field to a vocabulary.
    */
@@ -107,24 +169,33 @@ final class AccessByTaxonomyService {
       $entity_form_display_storage = $this->entityTypeManager->getStorage('entity_form_display');
 
       // Set the form display.
+      // Try to load the existing form display for the taxonomy term bundle:
       $form_display = $entity_form_display_storage->load('taxonomy_term.' . $vocabulary . '.default');
-      if ($form_display) {
-        if ($field_name == 'field_allowed_users') {
-          $form_display->setComponent($field_name, [
-            'type' => 'entity_reference_autocomplete',
-          ]);
-        }
-        else {
-          $form_display->setComponent($field_name, [
-            'type' => 'options_buttons',
-          ]);
-        }
-        try {
-          $form_display->save();
-        }
-        catch (EntityStorageException $e) {
-          $this->loggerChannelAccessByTaxonomy->error($e->getMessage());
-        }
+
+      if (!$form_display) {
+        // If the form display does not exist, create it:
+        $form_display = $entity_form_display_storage->create([
+          'targetEntityType' => 'taxonomy_term',
+          'bundle' => $vocabulary,
+          'mode' => 'default',
+          'status' => TRUE,
+        ]);
+      }
+      if ($field_name == 'field_allowed_users') {
+        $form_display->setComponent($field_name, [
+          'type' => 'entity_reference_autocomplete',
+        ]);
+      }
+      else {
+        $form_display->setComponent($field_name, [
+          'type' => 'options_buttons',
+        ]);
+      }
+      try {
+        $form_display->save();
+      }
+      catch (EntityStorageException $e) {
+        $this->loggerChannelAccessByTaxonomy->error($e->getMessage());
       }
 
       // Set the view display.