The event system

OrangeHRM uses Symfony's EventDispatcher for decoupled, in-process pub-sub. Services dispatch events; subscribers in any plugin can react. Two flavors of events flow through the same dispatcher:

1. Framework events (Symfony\Component\HttpKernel\KernelEvents) — request/controller/response/exception/terminate. Used by the auth + authorization + exception subscribers (see authorization skill).
2. OHRM domain events — EmployeeSavedEvent, LeaveApply, ModuleStatusChange, etc. Used by feature plugins to react to business actions. This is what new code typically interacts with.

This skill covers both. For the auth/authorization-specific subscribers, see authorization. For dispatching from services, see services.

The wiring — Framework\Event\EventDispatcher

namespace OrangeHRM\Framework\Event;

use Symfony\Component\EventDispatcher\EventDispatcher as BaseEventDispatcher;

class EventDispatcher extends BaseEventDispatcher {}

That's the whole class — a one-line subclass with zero customization. Registered as Services::EVENT_DISPATCHER in Framework::configureContainer() (see doctrine-bootstrap for the same DI container).

Two consumer-facing pieces:

namespace OrangeHRM\Framework\Event;

use Symfony\Component\EventDispatcher\EventSubscriberInterface;

abstract class AbstractEventSubscriber implements EventSubscriberInterface {}

Also a thin wrapper — implements EventSubscriberInterface from Symfony, which requires the static getSubscribedEvents() method.

And on the consumer side, EventDispatcherTrait (from OrangeHRM\Core\Traits) gives $this->getEventDispatcher() to any class that needs to dispatch.

Accessing the dispatcher

To dispatch (in a service)

use OrangeHRM\Core\Traits\EventDispatcherTrait;

class WidgetService
{
    use EventDispatcherTrait;

    public function saveWidget(Widget $widget): Widget
    {
        $widget = $this->getWidgetDao()->saveWidget($widget);
        $this->getEventDispatcher()->dispatch(
            new WidgetSavedEvent($widget),         // ← Event object (carries the payload)
            WidgetEvents::WIDGET_SAVED,             // ← Event name string
        );
        return $widget;
    }
}

Two-argument dispatch($event, $eventName):

• $event is the Event-extending object that carries data to listeners.
• $eventName is the string key listeners subscribe to.

To listen (in a subscriber class)

use OrangeHRM\Framework\Event\AbstractEventSubscriber;

class WidgetAuditSubscriber extends AbstractEventSubscriber
{
    public static function getSubscribedEvents(): array
    {
        return [
            WidgetEvents::WIDGET_SAVED => [['onSavedEvent', 0]],   // [methodName, priority]
        ];
    }

    public function onSavedEvent(WidgetSavedEvent $event): void
    {
        // react to the event
    }
}

getSubscribedEvents() returns [eventName => [[methodName, priority], ...]]. Same event can map to multiple methods at different priorities.

Defining events for your feature

Convention: each plugin has an Event/ directory with one <Plugin>Events.php constant-holder + one event class per event.

The constant-holder class

src/plugins/orangehrmPimPlugin/Event/EmployeeEvents.php:

namespace OrangeHRM\Pim\Event;

class EmployeeEvents
{
    /** @see \OrangeHRM\Pim\Event\EmployeeAddedEvent */
    public const EMPLOYEE_ADDED = 'pim.employee_added';

    /** @see \OrangeHRM\Pim\Event\EmployeeSavedEvent */
    public const EMPLOYEE_SAVED = 'pim.employee_saved';

    /** @see \OrangeHRM\Pim\Event\EmployeeDeletedEvent */
    public const EMPLOYEES_DELETED = 'pim.employees_deleted';

    /** @see \OrangeHRM\Pim\Event\EmployeeJoinedDateChangedEvent */
    public const JOINED_DATE_CHANGED = 'pim.employee_join_date_changed';
}

Naming:

• File: <Plugin>Events.php, class <Plugin>Events
• Constants: UPPER_SNAKE_CASE, value <plugin>.<event_name> (lowercase, dotted)
• @see PHPDoc pointing at the matching Event class — devs grep the constant to find the payload type

The event class

src/plugins/orangehrmPimPlugin/Event/EmployeeSavedEvent.php:

namespace OrangeHRM\Pim\Event;

use OrangeHRM\Entity\Employee;
use OrangeHRM\Framework\Event\Event;       // ← OHRM's Event base, thin wrapper around Symfony's

class EmployeeSavedEvent extends Event
{
    private Employee $employee;

    public function __construct(Employee $employee)
    {
        $this->employee = $employee;
    }

    public function getEmployee(): Employee
    {
        return $this->employee;
    }
}

Five-step shape:

1. Extends OrangeHRM\Framework\Event\Event (which extends Symfony's Event).
2. Constructor takes the payload data — typically an entity or a few primitives.
3. Read-only getters for whatever listeners need.
4. Don't put behavior on the event itself — events are immutable carriers.
5. Don't make the event class abstract unless multiple subclasses share the payload shape. For most events, a single concrete class is fine.

Event inheritance for "this is a special case of that"

EmployeeAddedEvent extends EmployeeSavedEvent:

class EmployeeAddedEvent extends EmployeeSavedEvent {}

Use this when you want listeners to be able to react to "any save" via the parent class and to "only the create-time save" via the subclass. Then dispatch the most-specific class:

$event = $isNew ? new EmployeeAddedEvent($employee) : new EmployeeSavedEvent($employee);
$this->getEventDispatcher()->dispatch($event, WhicheverEventName);

This is a real pattern in PIM but not common — most events stand alone.

Writing a subscriber

Two common locations:

Location	Use for
src/plugins/orangehrm{X}Plugin/Subscriber/<Name>Subscriber.php	Plugin-owned subscribers that react to events from this plugin or others.
src/plugins/orangehrmCorePlugin/Subscriber/<Name>Subscriber.php	Cross-cutting framework-level subscribers (the auth + authorization + exception + mailer subscribers all live here).

Class shape

namespace OrangeHRM\X\Subscriber;

use OrangeHRM\Framework\Event\AbstractEventSubscriber;
use OrangeHRM\Pim\Event\EmployeeEvents;
use OrangeHRM\Pim\Event\EmployeeSavedEvent;

class WidgetSyncOnEmployeeSaveSubscriber extends AbstractEventSubscriber
{
    public static function getSubscribedEvents(): array
    {
        return [
            EmployeeEvents::EMPLOYEE_SAVED => [['onEmployeeSaved', 0]],
        ];
    }

    public function onEmployeeSaved(EmployeeSavedEvent $event): void
    {
        $employee = $event->getEmployee();
        // … your reaction
    }
}

Or with multiple events + priorities (the LeaveEventSubscriber pattern):

public static function getSubscribedEvents(): array
{
    return [
        LeaveEvent::APPLY   => [['onAllocateEvent', 0]],
        LeaveEvent::ASSIGN  => [['onAllocateEvent', 0]],
        LeaveEvent::APPROVE => [['onStatusChangeEvent', 0]],
        LeaveEvent::CANCEL  => [['onStatusChangeEvent', 0]],
        LeaveEvent::REJECT  => [['onStatusChangeEvent', 0]],
    ];
}

One subscriber class can listen to multiple events and dispatch to different handler methods.

Method signature

The handler method receives the event object as its only argument (typed to the most specific class it expects):

public function onEmployeeSaved(EmployeeSavedEvent $event): void { … }

For Symfony KernelEvents, the argument is one of RequestEvent, ControllerEvent, ResponseEvent, ExceptionEvent, TerminateEvent. Examples in authorization skill.

Composing helpers into a subscriber

Subscribers are plain classes. Pull in traits the same way services do:

class WidgetAuditSubscriber extends AbstractEventSubscriber
{
    use LoggerTrait;
    use ConfigServiceTrait;
    use WidgetServiceTrait;

    public function onSavedEvent(WidgetSavedEvent $event): void
    {
        if ($this->getConfigService()->getAuditEnabled()) {
            $this->getLogger()->info('Widget saved: ' . $event->getWidget()->getId());
            $this->getWidgetService()->logAudit($event->getWidget());
        }
    }
}

Same DI access patterns as services (see services skill).

Registering subscribers — plugin boot

Subscribers don't auto-register from filesystem scans. Every subscriber must be explicitly added in some plugin's <Plugin>PluginConfiguration::initialize() to start receiving events.

namespace OrangeHRM\X;

use OrangeHRM\Core\Traits\EventDispatcherTrait;
use OrangeHRM\Framework\Http\Request;
use OrangeHRM\Framework\PluginConfigurationInterface;
use OrangeHRM\X\Subscriber\WidgetAuditSubscriber;

class XPluginConfiguration implements PluginConfigurationInterface
{
    use EventDispatcherTrait;

    public function initialize(Request $request): void
    {
        $this->getEventDispatcher()->addSubscriber(new WidgetAuditSubscriber());
        // … other initialization
    }
}

addSubscriber() takes an instance, not a class name. Don't worry about request-time vs boot-time instantiation — initialize() runs once per request before the dispatch happens.

Convention: register all of a plugin's own subscribers in that plugin's initialize(). The core plugin's CorePluginConfiguration has ~10 subscriber registrations covering the framework-wide subscribers (ExceptionSubscriber, ApiAuthorizationSubscriber, MailerSubscriber, etc.).

Conditional registration

Some subscribers only matter in certain contexts. Wrap in an if:

if (Config::isInstalled()) {
    $this->getEventDispatcher()->addSubscriber(new RegistrationEventPersistSubscriber());
}

The RegistrationEventPersistSubscriber (in CorePluginConfiguration) only registers post-install because it writes to a table that doesn't exist during initial install.

Priority and ordering

[methodName, priority] — higher priority runs first. Default 0.

Real priorities from the codebase:

• AuthenticationSubscriber::onControllerEvent — priority 100000 (runs first on every controller event)
• ApiAuthorizationSubscriber::onControllerEvent — priority 80000 (runs second)
• ScreenAuthorizationSubscriber::onControllerEvent — priority 80000 (same tier, order undefined between them)
• RouterListener::onKernelRequest — priority 99500 (routing happens early)
• RouterListener::onKernelException — priority -64 (lowest, fallback)

The numbers are large gaps on purpose — there's room to insert subscribers between 80000 and 100000 without re-numbering existing ones.

For OHRM domain events, priority is usually 0 because there's typically only one or two subscribers per event. Use larger priorities if you need to guarantee one subscriber sees the event before another.

Propagation control

A subscriber can stop further subscribers from receiving an event by calling $event->stopPropagation():

public function onExceptionEvent(ExceptionEvent $event): void
{
    if ($exception instanceof ForbiddenException) {
        $response = /* … build forbidden response … */;
        $event->setResponse($response);
        $event->stopPropagation();        // ← later subscribers won't see this exception
    }
}

Used heavily in the exception subscribers — once one of them has produced a response, the others shouldn't override it.

For domain events, propagation stopping is rare and usually wrong — multiple plugins might want to react to "employee saved" independently. Reach for it only when one subscriber's reaction makes others' invalid.

Symfony KernelEvents — the framework-level events

These fire for every HTTP request. Listed in priority of typical order of importance:

KernelEvent	When it fires	Common listeners
KernelEvents::REQUEST	Right after the request is parsed, before routing	RouterListener (routing), AuthenticationSubscriber::onRequestEvent (early bail-out for unauthenticated public routes)
KernelEvents::CONTROLLER	After routing resolved the controller, before invoking it	AuthenticationSubscriber::onControllerEvent (priority 100000), ApiAuthorizationSubscriber, ScreenAuthorizationSubscriber (priority 80000), RequestBodySubscriber (parses JSON body), ModuleNotAvailableSubscriber
KernelEvents::RESPONSE	After the controller produced a Response, before sending	Headers, logging, debugging
KernelEvents::EXCEPTION	When anything throws	RouterListener::onKernelException (404 handling), ApiAuthorizationSubscriber::onExceptionEvent (turns ForbiddenException into JSON 403), AuthenticationSubscriber::onExceptionEvent (turns SessionExpiredException into redirect), ExceptionSubscriber, RequestForwardableExceptionSubscriber
KernelEvents::TERMINATE	After the response is sent	Cleanup work that shouldn't delay the user
KernelEvents::FINISH_REQUEST	When a (sub-)request finishes	RouterListener::onKernelFinishRequest

If you find yourself needing to hook into one of these, look at the existing subscribers as templates — they're all in orangehrmCorePlugin/Subscriber/ and the auth plugin.

Where existing OHRM domain events live

Quick map (use this to figure out what events already exist before inventing new ones):

Plugin	Events file	Examples
Pim	Event/EmployeeEvents	EMPLOYEE_ADDED, EMPLOYEE_SAVED, EMPLOYEES_DELETED, JOINED_DATE_CHANGED
Leave	Event/LeaveEvent	APPLY, ASSIGN, APPROVE, CANCEL, REJECT, ALLOCATE
Maintenance	Event/MaintenanceEvent	PurgeEmployee
Core	Event/ModuleEvent	ModuleStatusChange (used by Dashboard plugin's three module-status subscribers)
Buzz	per-event classes	various

Before defining a new event, check if an existing one carries enough information. E.g., "I need to react when employee email changes" → just listen to EmployeeSavedEvent and compare against the prior state.

---

Recipes

Recipe 1 — Define and dispatch a new domain event

Constants:

// src/plugins/orangehrmXPlugin/Event/WidgetEvents.php
namespace OrangeHRM\X\Event;

class WidgetEvents
{
    /** @see \OrangeHRM\X\Event\WidgetSavedEvent */
    public const WIDGET_SAVED = 'x.widget_saved';

    /** @see \OrangeHRM\X\Event\WidgetDeletedEvent */
    public const WIDGET_DELETED = 'x.widget_deleted';
}

Event class:

// src/plugins/orangehrmXPlugin/Event/WidgetSavedEvent.php
namespace OrangeHRM\X\Event;

use OrangeHRM\Entity\Widget;
use OrangeHRM\Framework\Event\Event;

class WidgetSavedEvent extends Event
{
    public function __construct(private Widget $widget, private bool $isNew) {}
    public function getWidget(): Widget { return $this->widget; }
    public function isNew(): bool       { return $this->isNew; }
}

Dispatch from the service:

class WidgetService
{
    use EventDispatcherTrait;

    public function saveWidget(Widget $widget): Widget
    {
        $isNew  = !$widget->getId();
        $widget = $this->getWidgetDao()->saveWidget($widget);

        $this->getEventDispatcher()->dispatch(
            new WidgetSavedEvent($widget, $isNew),
            WidgetEvents::WIDGET_SAVED,
        );

        return $widget;
    }
}

Recipe 2 — React to an event with a subscriber

// src/plugins/orangehrmXPlugin/Subscriber/WidgetAuditSubscriber.php
namespace OrangeHRM\X\Subscriber;

use OrangeHRM\Core\Traits\LoggerTrait;
use OrangeHRM\Framework\Event\AbstractEventSubscriber;
use OrangeHRM\X\Event\WidgetEvents;
use OrangeHRM\X\Event\WidgetSavedEvent;

class WidgetAuditSubscriber extends AbstractEventSubscriber
{
    use LoggerTrait;

    public static function getSubscribedEvents(): array
    {
        return [
            WidgetEvents::WIDGET_SAVED => [['onSavedEvent', 0]],
        ];
    }

    public function onSavedEvent(WidgetSavedEvent $event): void
    {
        $action = $event->isNew() ? 'created' : 'updated';
        $this->getLogger()->info("Widget {$event->getWidget()->getId()} $action");
    }
}

Register in the plugin's configuration:

public function initialize(Request $request): void
{
    $this->getEventDispatcher()->addSubscriber(new WidgetAuditSubscriber());
}

Recipe 3 — Cross-plugin subscriber (react to another plugin's event)

The dashboard plugin reacts to module status changes from core:

namespace OrangeHRM\Dashboard\Subscriber;

use OrangeHRM\Core\Event\ModuleEvent;
use OrangeHRM\Core\Event\ModuleStatusChange;
use OrangeHRM\Framework\Event\AbstractEventSubscriber;

class BuzzModuleStatusChangeSubscriber extends AbstractEventSubscriber
{
    public static function getSubscribedEvents(): array
    {
        return [
            ModuleEvent::MODULE_STATUS_CHANGE => [['onStatusChange', 0]],
        ];
    }

    public function onStatusChange(ModuleStatusChange $event): void
    {
        if ($event->getModule() === 'buzz') {
            // toggle buzz-related dashboard widgets
        }
    }
}

Register in the consuming plugin's <Plugin>PluginConfiguration::initialize() (dashboard, not core). The producer doesn't need to know who's listening.

Recipe 4 — Listen to a Symfony KernelEvents event

namespace OrangeHRM\X\Subscriber;

use OrangeHRM\Framework\Event\AbstractEventSubscriber;
use Symfony\Component\HttpKernel\Event\ResponseEvent;
use Symfony\Component\HttpKernel\KernelEvents;

class RequestTimingSubscriber extends AbstractEventSubscriber
{
    public static function getSubscribedEvents(): array
    {
        return [
            KernelEvents::RESPONSE => [['onResponse', -100]],          // run after most listeners
        ];
    }

    public function onResponse(ResponseEvent $event): void
    {
        $response = $event->getResponse();
        $response->headers->set('X-Render-Time', $this->renderTime());
    }
}

Negative priority runs late (after most other RESPONSE listeners). Positive runs early.

Recipe 5 — Stop propagation when handling an exception

class WidgetExceptionSubscriber extends AbstractEventSubscriber
{
    public static function getSubscribedEvents(): array
    {
        return [KernelEvents::EXCEPTION => [['onException', 10]]];
    }

    public function onException(ExceptionEvent $event): void
    {
        if ($event->getThrowable() instanceof WidgetSpecificException) {
            $event->setResponse(new Response('Widget error', 400));
            $event->stopPropagation();
        }
    }
}

Only stop propagation when you've handled the case completely. Generic logging subscribers should never stop propagation.

---

Checklists

Define a new event

• Create or extend <Plugin>Events.php constant-holder; constants UPPER_SNAKE_CASE, values <plugin>.<name>
• Create event class in <Plugin>Plugin/Event/<Name>Event.php extending OrangeHRM\Framework\Event\Event
• Constructor takes the payload; getters expose it; no behavior on the event class itself
• PHPDoc @see from the constant to the event class
• Dispatch via $this->getEventDispatcher()->dispatch(new <Name>Event(...), <Plugin>Events::<NAME>) from a service
• If subclassing for "special case": child's constructor calls parent's; listeners typing the parent will still match

Write a new subscriber

• Class in plugin's Subscriber/ directory extending AbstractEventSubscriber
• getSubscribedEvents() returns [eventName => [[method, priority]]] shape
• Handler method signature typed to the most specific event class
• Trait composition for any helpers/services needed
• Register in the plugin's <Plugin>PluginConfiguration::initialize() via $this->getEventDispatcher()->addSubscriber(new <Name>Subscriber())

Debug "my subscriber isn't firing"

• Is the subscriber registered? Search for addSubscriber(new MyClass( in PluginConfiguration files. Missing registration is the most common cause.
• Does the event name match exactly? Compare what you dispatched (<Plugin>Events::X) with what you subscribed to. Typo here is silent — Symfony's dispatcher has no "unknown event" warning.
• Is the subscriber's plugin configuration loaded? Plugins are loaded based on ohrm_plugin_configs (see doctrine-bootstrap); a plugin that isn't registered won't have its subscribers wired up.
• Is propagation stopped earlier? Higher-priority subscribers can call stopPropagation() and you wouldn't see it. Add a temporary error_log in your handler to confirm the priority comparison.
• For KernelEvents — is your priority placing you before the response was set? Some event handlers exit early if $event->hasResponse() is true.

Things that bite

• No "magic" subscriber discovery. Subscribers don't auto-register based on filesystem location. The explicit addSubscriber() call in <Plugin>PluginConfiguration::initialize() is the only thing that wires them up. Drop a .php file in Subscriber/ and walk away → it never fires.
• Event name strings are case-sensitive and unvalidated. 'pim.employee_saved' ≠ 'pim.employee_Saved'. Always use the constant from <Plugin>Events:: on both sides.
• $event->stopPropagation() is sticky for the rest of the dispatch. Subsequent subscribers for the same event won't run. Use sparingly — generally the producer shouldn't decide who else gets to react.
• Multiple subscribers at the same priority have undefined order. If order matters, use different priorities. Don't rely on file alphabetical order or registration order.
• Dispatching an event with no listeners is silent and cheap. Don't add events "just in case someone might want to listen later" — they're free, but each one is a class file someone has to maintain.
• Listeners run synchronously and in-process. A slow listener slows the request. For heavy work, fire the event but have the subscriber queue a job (see mail skill's queue pattern + scheduled-jobs).
• Domain events fire only when the service dispatches them. A direct DAO call ($this->getEmployeeDao()->saveEmployee(...) from somewhere other than EmployeeService) bypasses the event. Keep persistence-with-event-side-effects in the service layer.