Events
Events are used to communicate between different aspects of the Nextcloud eco system. They are used in the Nextcloud server internally, for server-to-apps communcation as well as inter-app communication.
Overview
The term “events” is a bit broad in Nextcloud and there are multiple ways of emitting them.
OCP event dispatcher
This mechanism is a versatile and typed approach to events in Nextcloud’s php code. It uses objects rather than just passing primitives or untyped arrays. This should help provide a better developer experience while lowering the risk of unexpected changes in the API that are hard to find after the initial implementation.
Naming scheme
The name should reflect the subject and the actions. Suffixing event classes with Event makes it easier to recognize their purpose.
For example, if a user is created, a UserCreatedEvent will be emitted.
Events are usually evmitted after the event has happened. If it’s emitted before, it should be prefixed with Before.
Thus BeforeUserCreatedEvent is emitted before the user data is written to the database.
Note
Although you may choose to name your event classes differently, sticking to the convention will allow Nextcloud developers understand each other’s apps more easily.
Note
For backwards compatibility with the Symfony class GenericEvent, Nextcloud also provides a \OCP\EventDispatcher\Event class. With the release of Nextcloud 22 this class has been deprecated. Named and typed event classes should be used instead.
Writing events
As a rule events are dedicated classes extending \OCP\EventDispatcher\Event.
<?php
use OCP\EventDispatcher\Event;
namespace OCA\MyApp\Event;
class AddEvent extends Event {}
The event above allows signalling that something happened. But in many cases you want to actually transport data like the affected resource with the event. Then the events act as simple data transfer objects. Therefore they need a constructor that takes the arguments, private members to store them and getters to access the values in listeners.
<?php
use OCP\EventDispatcher\Event;
use OCP\IUser;
class UserCreatedEvent extends Event {
private IUser $user;
public function __construct(IUser $user) {
parent::__construct();
$this->user = $user;
}
public function getUser(): IUser {
return $this->user;
}
}
Writing a listener
A listener can be a simple callback function (or anything else that is callable, or a dedicated class.
Listener callbacks
You can use simple callback to react on events. They will receive the event object as first and only parameter. You can type-hint the base Event class or the subclass you expect and register for.
<?php
use OCA\MyApp\Event\AddEvent;
use OCP\AppFramework\App;
use OCP\EventDispatcher\IEventDispatcher;
namespace OCA\MyApp\AppInfo;
class Application extends App {
public function __construct() {
parent::__construct('myapp');
/* @var IEventDispatcher $eventDispatcher */
$dispatcher = $this->getContainer()->query(IEventDispatcher::class);
$dispatcher->addListener(AddEvent::class, function(AddEvent $event) {
// ...
});
}
}
Note
Type-hinting the actual event class will give you better IDE and static analyzers support. It’s generally safe to assume the dispatcher will not give you any other objects.
Listener classes
A class that can handle an event will implement the \OCP\EventDispatcher\IEventListener interface. Class names should end with Listener.
<?php
use OCA\MyApp\Event\AddEvent;
use OCP\EventDispatcher\Event;
use OCP\EventDispatcher\IEventListener;
namespace OCA\MyApp\Event;
class AddTwoListener implements IEventListener {
public function handle(Event $event): void {
if (!($event instanceOf AddEvent)) {
return;
}
$event->addToCounter(2);
}
}
Note
Php parameter type hints are not allowed to be more specific than the type hints on the interface, thus you can’t use AddEvent in the method signature but use an instanceOf instead.
In the Application.php the event and the listener class are connected. The class is instantiated only when the actual event is fired.
<?php
use OCA\MyApp\Event\AddEvent;
use OCA\MyApp\Listener\AddTwoListener;
use OCP\AppFramework\App;
use OCP\EventDispatcher\IEventDispatcher;
namespace OCA\MyApp\AppInfo;
class Application extends App {
public function __construct() {
parent::__construct('myapp');
/* @var IEventDispatcher $eventDispatcher */
$dispatcher = $this->getContainer()->get(IEventDispatcher::class);
$dispatcher->addServiceListener(AddEvent::class, AddTwoListener::class);
}
}
Note
The listener is resolved via the DI container, therefore you can add a constructor and type-hint services required for processing the event.
Available Events
Here you find an overview of the public events that can be consumed in apps. See their source files for more details.
\OCA\DAV\Events\AddressBookCreatedEvent
New in version 20.
This event is triggered when a user creates a new address-book.
\OCA\DAV\Events\AddressBookDeletedEvent
New in version 20.
This event is triggered when a user deletes an address-book.
\OCA\DAV\Events\AddressBookUpdatedEvent
New in version 20.
This event is triggered when a user updates an address-book.
\OCA\DAV\Events\CachedCalendarObjectCreatedEvent
New in version 20.
This event is triggered when a cached calendar object is being created while fetching a calendar-subscription.
\OCA\DAV\Events\CachedCalendarObjectDeletedEvent
New in version 20.
This event is triggered when a cached calendar object is being deleted while fetching a calendar-subscription.
\OCA\DAV\Events\CachedCalendarObjectUpdatedEvent
New in version 20.
This event is triggered when a cached calendar object is being updated while fetching a calendar-subscription.
\OCA\DAV\Events\CalendarCreatedEvent
New in version 20.
This event is triggered when a user creates a new calendar.
\OCA\DAV\Events\CalendarDeletedEvent
New in version 20.
This event is triggered when a user deletes a calendar.
\OCA\DAV\Events\CalendarObjectCreatedEvent
New in version 20.
This event is triggered when a user creates a calendar-object.
\OCA\DAV\Events\CalendarObjectDeletedEvent
New in version 20.
This event is triggered when a user deletes a calendar-object.
\OCA\DAV\Events\CalendarObjectUpdatedEvent
New in version 20.
This event is triggered when a user updates a calendar-object.
\OCA\DAV\Events\CalendarPublishedEvent
New in version 20.
This event is triggered when a user publishes a calendar.
\OCA\DAV\Events\CalendarUnpublishedEvent
New in version 20.
This event is triggered when a user unpublishes calendar.
\OCA\DAV\Events\CalendarUpdatedEvent
New in version 20.
This event is triggered when a user updates a calendar.
\OCA\DAV\Events\CardCreatedEvent
New in version 20.
This event is triggered when a user creates a new card in an address-book.
\OCA\DAV\Events\CardDeletedEvent
New in version 20.
This event is triggered when a user deletes a card in an address-book.
\OCA\DAV\Events\CardUpdatedEvent
New in version 20.
This event is triggered when a user updates a card in an address-book.
\OCA\DAV\Events\SabrePluginAuthInitEvent
New in version 20.
This event is triggered during the setup of the SabreDAV server to allow the registration of additional authentication backends.
OCP\BeforeSabrePubliclyLoadedEvent
New in version 26.
This event is triggered when accessing public webdav endpoints.
\OCA\DAV\Events\SubscriptionCreatedEvent
New in version 20.
This event is triggered when a user creates a new calendar-subscription.
\OCA\DAV\Events\SubscriptionDeletedEvent
New in version 20.
This event is triggered when a user deletes a calendar-subscription.
\OCA\DAV\Events\SubscriptionUpdatedEvent
New in version 20.
This event is triggered when a user deletes a calendar-subscription.
\OCA\Files\Event\LoadAdditionalScriptsEvent
New in version 17.
This event is triggered when the files app is rendered. It can be used to add additional scripts to the files app.
\OCA\Files_Sharing\Event\BeforeTemplateRenderedEvent
New in version 20.
Emitted before the rendering step of the public share page happens. The event holds a flag that specifies if it is the authentication page of a public share.
\OCA\Settings\Events\BeforeTemplateRenderedEvent
New in version 20.
This event is triggered right before the user management template is rendered.
\OCA\User_LDAP\Events\GroupBackendRegistered
New in version 20.
This event is triggered right after the LDAP group backend is registered.
\OCA\User_LDAP\Events\UserBackendRegistered
New in version 20.
This event is triggered right after the LDAP user backend is registered.
\OCA\Viewer\Event\LoadViewer
New in version 17.
This event is triggered whenever the viewer is loaded and extensions should be loaded.
\OCP\App\Events\AppEnableEvent
New in version 27.
This event is triggered when an app is enabled.
\OCP\App\Events\AppUpdateEvent
New in version 27.
This event is triggered when an app is updated.
\OCP\App\Events\AppDisableEvent
New in version 27.
This event is triggered when an app is disabled.
\OCP\AppFramework\Http\Events\BeforeTemplateRenderedEvent
New in version 20.
Emitted before the rendering step of each TemplateResponse. The event holds a flag that specifies if an user is logged in.
\OCP\Authentication\Events\LoginFailedEvent
New in version 19.
Emitted when the authentication fails, but only if the login name can be associated with an existing user.
\OCP\Authentication\TwoFactorAuth\TwoFactorProviderDisabled
New in version 20.
\OCP\Collaboration\Reference\RenderReferenceEvent
New in version 25.
Event emitted when apps might render references like link previews or smart picker widgets.
This can be used to inject scripts for extending that. Further details can be found in the Reference providers deep dive.
\OCP\Contacts\Events\ContactInteractedWithEvent
New in version 19.
Event emitted by apps whenever there was an interaction with another user or contact.
It is an event that allows apps to notify other components about an interaction between two users. This can be used to build better recommendations and suggestions in user interfaces.
Emitters should add at least one identifier (uid, email, federated cloud ID) of the recipient of the interaction.
\OCP\DirectEditing\RegisterDirectEditorEvent
New in version 18.
Event to allow to register the direct editor.
\OCP\Files\Events\BeforeFileScannedEvent
New in version 18.
\OCP\Files\Events\BeforeFolderScannedEvent
New in version 18.
\OCP\Files\Events\FileCacheUpdated
New in version 18.
\OCP\Files\Events\FileScannedEvent
New in version 18.
\OCP\Files\Events\FolderScannedEvent
New in version 18.
\OCP\Files\Events\NodeAddedToCache
New in version 18.
\OCP\Files\Events\NodeRemovedFromCache
New in version 18.
\OCP\Group\Events\BeforeGroupCreatedEvent
New in version 18.
\OCP\Group\Events\BeforeGroupDeletedEvent
New in version 18.
\OCP\Group\Events\BeforeUserAddedEvent
New in version 18.
\OCP\Group\Events\BeforeUserRemovedEvent
New in version 18.
Deprecated in 20.0.0 - it can’t be guaranteed that this event is triggered in all case (e.g. for LDAP users this isn’t possible)
\OCP\Group\Events\GroupCreatedEvent
New in version 26.
\OCP\Group\Events\GroupChangedEvent
New in version 18.
\OCP\Group\Events\GroupDeletedEvent
New in version 18.
\OCP\Group\Events\SubAdminAddedEvent
New in version 21.
\OCP\Group\Events\SubAdminRemovedEvent
New in version 21.
\OCP\Group\Events\UserAddedEvent
New in version 18.
\OCP\Group\Events\UserRemovedEvent
New in version 18.
\OCP\Mail\Events\BeforeMessageSent
New in version 19.
Emitted before a system mail is sent. It can be used to alter the message.
OCP\Preview\BeforePreviewFetchedEvent
New in version 26.
Emitted before a file preview is being fetched. It can be used to block preview rendering by throwing a OCP\Files\NotFoundException.
\OCP\Security\CSP\AddContentSecurityPolicyEvent
New in version 17.
Allows to inject something into the default content policy. This is for example useful when you’re injecting Javascript code into a view belonging to another controller and cannot modify its Content-Security-Policy itself. Note that the adjustment is only applied to applications that use AppFramework controllers.
WARNING: Using this API incorrectly may make the instance more insecure. Do think twice before adding whitelisting resources. Please do also note that it is not possible to use the disallowXYZ functions.
\OCP\Security\Events\GenerateSecurePasswordEvent
New in version 18.
\OCP\Security\Events\ValidatePasswordPolicyEvent
New in version 18.
\OCP\Security\FeaturePolicy\AddFeaturePolicyEvent
New in version 17.
Event that allows to register a feature policy header to a request.
\OCP\User\Events\BeforePasswordUpdatedEvent
New in version 18.
Emitted before the user password is updated.
\OCP\User\Events\PasswordUpdatedEvent
New in version 18.
Emitted when the user password has been updated.
\OCP\User\Events\BeforeUserCreatedEvent
New in version 18.
Emitted before a new user is created on the back-end.
\OCP\User\Events\UserCreatedEvent
New in version 18.
Emitted when a new user has been created on the back-end.
\OCP\User\Events\BeforeUserDeletedEvent
New in version 18.
\OCP\User\Events\UserDeletedEvent
New in version 18.
\OCP\User\Events\BeforeUserLoggedInEvent
New in version 18.
\OCP\User\Events\BeforeUserLoggedOutEvent
New in version 18.
Emitted before a user is logged out.
\OCP\User\Events\PostLoginEvent
New in version 18.
\OCP\User\Events\UserChangedEvent
New in version 18.
\OCP\User\Events\UserLiveStatusEvent
New in version 20.
\OCP\User\Events\UserLoggedInEvent
New in version 18.
\OCP\User\Events\UserLoggedOutEvent
New in version 18.
Emitted when a user has been logged out successfully.
\OCP\WorkflowEngine\LoadSettingsScriptsEvent
New in version 20.
Emitted when the workflow engine settings page is loaded.
\OCP\WorkflowEngine\RegisterChecksEvent
New in version 18.
\OCP\WorkflowEngine\RegisterEntitiesEvent
New in version 18.
\OCP\WorkflowEngine\RegisterOperationsEvent
New in version 18.
Symfony event dispatcher
Warning
Using the Symfony event dispatcher mechanism is discouraged. Use the OCP event dispatcher abstraction instead.
tbd
Hooks
Deprecated since version 18: Use the OCP event dispatcher instead.
Hooks are used to execute code before or after an event has occurred. This is for instance useful to run cleanup code after users, groups or files have been deleted. Hooks should be registered in the app.php:
<?php
namespace OCA\MyApp\AppInfo;
$app = new Application();
$app->getContainer()->query('UserHooks')->register();
The hook logic should be in a separate class that is being registered in the App constructor:
<?php
namespace OCA\MyApp\AppInfo;
use \OCP\AppFramework\App;
use \OCA\MyApp\Hooks\UserHooks;
class Application extends App {
public function __construct(array $urlParams=array()){
parent::__construct('myapp', $urlParams);
$container = $this->getContainer();
/**
* Controllers
*/
$container->registerService('UserHooks', function($c) {
return new UserHooks(
$c->get(\OCP\IUserManager::class)
);
});
}
}
<?php
namespace OCA\MyApp\Hooks;
use OCP\IUserManager;
class UserHooks {
private $userManager;
public function __construct(IUserManager $userManager){
$this->userManager = $userManager;
}
public function register() {
$callback = function($user) {
// your code that executes before $user is deleted
};
$this->userManager->listen('\OC\User', 'preDelete', $callback);
}
}
Available hooks
The scope is the first parameter that is passed to the listen method, the second parameter is the method and the third one the callback that should be executed once the hook is being called, e.g.:
<?php
// listen on user predelete
$callback = function($user) {
// your code that executes before $user is deleted
};
$userManager->listen('\OC\User', 'preDelete', $callback);
Hooks can also be removed by using the removeListener method on the object:
<?php
// delete previous callback
$userManager->removeListener(null, null, $callback);
The following hooks are available:
Session
Injectable from the ServerContainer with the \OCP\IUserSession service.
Hooks available in scope \OC\User:
preSetPassword (\OC\User\User $user, string $password, string $recoverPassword)
postSetPassword (\OC\User\User $user, string $password, string $recoverPassword)
changeUser (\OC\User\User $user, string $feature, string $value)
preDelete (\OC\User\User $user)
postDelete (\OC\User\User $user)
preCreateUser (string $uid, string $password)
postCreateUser (\OC\User\User $user)
preLogin (string $user, string $password)
postLogin (\OC\User\User $user, string $password)
logout ()
UserManager
Injectable from the ServerContainer with the \OCP\IUserManager service.
Hooks available in scope \OC\User:
preSetPassword (\OC\User\User $user, string $password, string $recoverPassword)
postSetPassword (\OC\User\User $user, string $password, string $recoverPassword)
preDelete (\OC\User\User $user)
postDelete (\OC\User\User $user)
preCreateUser (string $uid, string $password)
postCreateUser (\OC\User\User $user, string $password)
GroupManager
Hooks available in scope \OC\Group:
preAddUser (\OC\Group\Group $group, \OC\User\User $user)
postAddUser (\OC\Group\Group $group, \OC\User\User $user)
preRemoveUser (\OC\Group\Group $group, \OC\User\User $user)
postRemoveUser (\OC\Group\Group $group, \OC\User\User $user)
preDelete (\OC\Group\Group $group)
postDelete (\OC\Group\Group $group)
preCreate (string $groupId)
postCreate (\OC\Group\Group $group)
Filesystem root
Injectable from the ServerContainer by calling the method getRootFolder(), getUserFolder() or getAppFolder().
To enable these events for your app you should add the following to your info.xml file:
<types>
<filesystem/>
</types>
Filesystem hooks available in scope \OC\Files:
preWrite (\OCP\Files\Node $node)
postWrite (\OCP\Files\Node $node)
preCreate (\OCP\Files\Node $node)
postCreate (\OCP\Files\Node $node)
preDelete (\OCP\Files\Node $node)
postDelete (\OCP\Files\Node $node)
preTouch (\OCP\Files\Node $node, int $mtime)
postTouch (\OCP\Files\Node $node)
preCopy (\OCP\Files\Node $source, \OCP\Files\Node $target)
postCopy (\OCP\Files\Node $source, \OCP\Files\Node $target)
preRename (\OCP\Files\Node $source, \OCP\Files\Node $target)
postRename (\OCP\Files\Node $source, \OCP\Files\Node $target)
Filesystem scanner
Filesystem scanner hooks available in scope \OC\Files\Utils\Scanner:
scanFile (string $absolutePath)
scanFolder (string $absolutePath)
postScanFile (string $absolutePath)
postScanFolder (string $absolutePath)
Public emitter
Deprecated since version 18: Use the OCP event dispatcher instead.
tbd