User accounts, permissions, and roles in Drupal 8

Same name and namespace in other branches

1. 9 core/core.api.php \user_api

API for user accounts, access checking, roles, and permissions.

Overview and terminology

Drupal's permission system is based on the concepts of accounts, roles, and permissions.

Users (site visitors) have accounts, which include a user name, an email address, a password (or some other means of authentication), and possibly other fields (if defined on the site). Anonymous users have an implicit account that does not have a real user name or any account information.

Each user account is assigned one or more roles. The anonymous user account automatically has the anonymous user role; real user accounts automatically have the authenticated user role, plus any roles defined on the site that they have been assigned.

Each role, including the special anonymous and authenticated user roles, is granted one or more named permissions, which allow them to perform certain tasks or view certain content on the site. It is possible to designate a role to be the "administrator" role; if this is set up, this role is automatically granted all available permissions whenever a module is enabled that defines permissions.

All code in Drupal that allows users to perform tasks or view content must check that the current user has the correct permission before allowing the action. In the standard case, access checking consists of answering the question "Does the current user have permission 'foo'?", and allowing or denying access based on the answer. Note that access checking should nearly always be done at the permission level, not by checking for a particular role or user ID, so that site administrators can set up user accounts and roles appropriately for their particular sites.

Defining permissions

Modules define permissions via a $module.permissions.yml file. See \Drupal\user\PermissionHandler for documentation of permissions.yml files.

Access permission checking

Depending on the situation, there are several methods for ensuring that access checks are done properly in Drupal:

• Routes: When you register a route, include a 'requirements' section that either gives the machine name of the permission that is needed to visit the URL of the route, or tells Drupal to use an access check method or service to check access. See the Routing topic for more information.
• Entities: Access for various entity operations is designated either with simple permissions or access control handler classes in the entity annotation. See the Entity API topic for more information.
• Other code: There is a 'current_user' service, which can be injected into classes to provide access to the current user account (see the Services and Dependency Injection topic for more information on dependency injection). In code that cannot use dependency injection, you can access this service and retrieve the current user account object by calling \Drupal::currentUser(). Once you have a user object for the current user (implementing \Drupal\user\UserInterface), you can call inherited method \Drupal\Core\Session\AccountInterface::hasPermission() to check permissions, or pass this object into other functions/methods.
• Forms: Each element of a form array can have a Boolean '#access' property, which determines whether that element is visible and/or usable. This is a common need in forms, so the current user service (described above) is injected into the form base class as method \Drupal\Core\Form\FormBase::currentUser().

User and role objects

User objects in Drupal are entity items, implementing \Drupal\user\UserInterface. Role objects in Drupal are also entity items, implementing \Drupal\user\RoleInterface. See the Entity API topic for more information about entities in general (including how to load, create, modify, and query them).

Roles often need to be manipulated in automated test code, such as to add permissions to them. Here's an example:

$role = \Drupal\user\Entity\Role::load('authenticated');
$role
  ->grantPermission('access comments');
$role
  ->save();

Other important interfaces:

• \Drupal\Core\Session\AccountInterface: The part of UserInterface that deals with access checking. In writing code that checks access, your method parameters should use this interface, not UserInterface.
• \Drupal\Core\Session\AccountProxyInterface: The interface for the current_user service (described above).

File

core/core.api.php, line 639

Documentation landing page and topics, plus core library hooks.

Interfaces