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Events
Doctrine ORM features a lightweight event system that is part of the Common package. Doctrine uses it to dispatch system events, mainly lifecycle events. You can also use it for your own custom events.
The Event System
The event system is controlled by the EventManager
. It is the
central point of Doctrine's event listener system. Listeners are
registered on the manager and events are dispatched through the
manager.
Now we can add some event listeners to the $evm
. Let's create a
TestEvent
class to play around with.
1 <?php
class TestEvent
{
const preFoo = 'preFoo';
const postFoo = 'postFoo';
private $_evm;
public $preFooInvoked = false;
public $postFooInvoked = false;
public function __construct($evm)
{
$evm->addEventListener(array(self::preFoo, self::postFoo), $this);
}
public function preFoo(EventArgs $e)
{
$this->preFooInvoked = true;
}
public function postFoo(EventArgs $e)
{
$this->postFooInvoked = true;
}
}
// Create a new instance
$test = new TestEvent($evm);
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Events can be dispatched by using the dispatchEvent()
method.
You can easily remove a listener with the removeEventListener()
method.
The Doctrine ORM event system also has a simple concept of event
subscribers. We can define a simple TestEventSubscriber
class
which implements the \Doctrine\Common\EventSubscriber
interface
and implements a getSubscribedEvents()
method which returns an
array of events it should be subscribed to.
1 <?php
use Doctrine\Common\EventSubscriber;
class TestEventSubscriber implements EventSubscriber
{
public $preFooInvoked = false;
public function preFoo()
{
$this->preFooInvoked = true;
}
public function getSubscribedEvents()
{
return array(TestEvent::preFoo);
}
}
$eventSubscriber = new TestEventSubscriber();
$evm->addEventSubscriber($eventSubscriber);
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The array to return in the |
Now when you dispatch an event, any event subscribers will be notified for that event.
Now you can test the $eventSubscriber
instance to see if the
preFoo()
method was invoked.
Registering Event Handlers
There are two ways to set up an event handler:
- For all events you can create a Lifecycle Event Listener or Subscriber class and register
it by calling $eventManager->addEventListener()
or eventManager->addEventSubscriber()
,
see
Listening and subscribing to Lifecycle Events
For some events (see table below), you can create a Lifecycle Callback* method in the
entity, see Lifecycle Callbacks.
Events Overview
Event | Dispatched by | Lifecycle Callback | Passed Argument |
---|---|---|---|
preRemove | $em->remove() |
Yes | PreRemoveEventArgs |
postRemove | $em->flush() |
Yes | PostRemoveEventArgs |
prePersist | $em->persist()
on initial persist |
Yes | PrePersistEventArgs |
postPersist | $em->flush() |
Yes | PostPersistEventArgs |
preUpdate | $em->flush() |
Yes | PreUpdateEventArgs |
postUpdate | $em->flush() |
Yes | PostUpdateEventArgs |
postLoad | Loading from database | Yes | PostLoadEventArgs |
loadClassMetadata | Loading of mapping metadata | No | LoadClassMetadataEventArgs |
onClassMetadataNotFound |
MappingException |
No | OnClassMetadataNotFoundEventArgs |
preFlush | $em->flush() |
Yes | PreFlushEventArgs |
onFlush | $em->flush() |
No | OnFlushEventArgs |
postFlush | $em->flush() |
No | PostFlushEventArgs |
onClear | $em->clear() |
No | OnClearEventArgs |
Naming convention
Events being used with the Doctrine ORM EventManager are best named with camelcase and the value of the corresponding constant should be the name of the constant itself, even with spelling. This has several reasons:
- It is easy to read.
- Simplicity.
- Each method within an EventSubscriber is named after the corresponding constant's value. If the constant's name and value differ it contradicts the intention of using the constant and makes your code harder to maintain.
An example for a correct notation can be found in the example
TestEvent
above.
Lifecycle Callbacks
Lifecycle Callbacks are defined on an entity class. They allow you to trigger callbacks whenever an instance of that entity class experiences a relevant lifecycle event. More than one callback can be defined for each lifecycle event. Lifecycle Callbacks are best used for simple operations specific to a particular entity class's lifecycle.
Lifecycle Callbacks are not supported for Embeddables. |
1 <?php
use Doctrine\DBAL\Types\Types;
use Doctrine\ORM\Event\PrePersistEventArgs;
use Doctrine\ORM\Mapping\Entity;
use Doctrine\ORM\Mapping\HasLifecycleCallbacks;
use Doctrine\ORM\Mapping\PrePersist;
use Doctrine\ORM\Mapping\PreUpdate;
#[Entity]
#[HasLifecycleCallbacks]
class User
{
// ...
#[Column(type: Types::STRING, length: 255)]
public $value;
#[PrePersist]
public function doStuffOnPrePersist(PrePersistEventArgs $eventArgs)
{
$this->createdAt = date('Y-m-d H:i:s');
}
#[PrePersist]
public function doOtherStuffOnPrePersist()
{
$this->value = 'changed from prePersist callback!';
}
#[PreUpdate]
public function doStuffOnPreUpdate(PreUpdateEventArgs $eventArgs)
{
$this->value = 'changed from preUpdate callback!';
}
}
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Lifecycle Callbacks Event Argument
The triggered event is also given to the lifecycle-callback.
With the additional argument you have access to the
EntityManager
and UnitOfWork
APIs inside these callback methods.
Listening and subscribing to Lifecycle Events
Lifecycle event listeners are much more powerful than the simple lifecycle callbacks that are defined on the entity classes. They sit at a level above the entities and allow you to implement re-usable behaviors across different entity classes.
Note that they require much more detailed knowledge about the inner
workings of the EntityManager
and UnitOfWork
classes. Please
read the Implementing Event Listeners section
carefully if you are trying to write your own listener.
For event subscribers, there are no surprises. They declare the
lifecycle events in their getSubscribedEvents
method and provide
public methods that expect the relevant arguments.
A lifecycle event listener looks like the following:
1 <?php
use Doctrine\ORM\Event\PreUpdateEventArgs;
class MyEventListener
{
public function preUpdate(PreUpdateEventArgs $args)
{
$entity = $args->getObject();
$entityManager = $args->getObjectManager();
// perhaps you only want to act on some "Product" entity
if ($entity instanceof Product) {
// do something with the Product
}
}
}
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A lifecycle event subscriber may look like this:
1 <?php
use Doctrine\ORM\Event\PostUpdateEventArgs;
use Doctrine\ORM\Events;
use Doctrine\EventSubscriber;
class MyEventSubscriber implements EventSubscriber
{
public function getSubscribedEvents()
{
return array(
Events::postUpdate,
);
}
public function postUpdate(PostUpdateEventArgs $args)
{
$entity = $args->getObject();
$entityManager = $args->getObjectManager();
// perhaps you only want to act on some "Product" entity
if ($entity instanceof Product) {
// do something with the Product
}
}
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Lifecycle events are triggered for all entities. It is the responsibility of the listeners and subscribers to check if the entity is of a type it wants to handle. |
To register an event listener or subscriber, you have to hook it into the EventManager that is passed to the EntityManager factory:
You can also retrieve the event manager instance after the EntityManager was created:
Implementing Event Listeners
This section explains what is and what is not allowed during
specific lifecycle events of the UnitOfWork
class. Although you get
passed the EntityManager
instance in all of these events, you have
to follow these restrictions very carefully since operations in the
wrong event may produce lots of different errors, such as inconsistent
data and lost updates/persists/removes.
For the described events that are also lifecycle callback events
the restrictions apply as well, with the additional restriction
that (prior to version 2.4) you do not have access to the
EntityManager
or UnitOfWork
APIs inside these events.
prePersist
There are two ways for the prePersist
event to be triggered:
- One is when you call
EntityManager::persist()
. The event is also called for all cascaded associations. - The other is inside the
flush()
method when changes to associations are computed and this association is marked as cascade: persist. Any new entity found during this operation is also persisted andprePersist
called on it. This is called persistence by reachability.
In both cases you get passed a PrePersistEventArgs
instance
which has access to the entity and the entity manager.
This event is only triggered on initial persist of an entity (i.e. it does not trigger on future updates).
The following restrictions apply to prePersist
:
- If you are using a PrePersist Identity Generator such as sequences the ID value will NOT be available within any PrePersist events.
- Doctrine will not recognize changes made to relations in a prePersist event. This includes modifications to collections such as additions, removals or replacement.
preRemove
The preRemove
event is called on every entity immediately when it is passed
to the EntityManager::remove()
method. It is cascaded for all
associations that are marked as cascade: remove
It is not called for a DQL DELETE
statement.
There are no restrictions to what methods can be called inside the
preRemove
event, except when the remove method itself was
called during a flush operation.
preFlush
preFlush
is called inside EntityManager::flush()
before
anything else. EntityManager::flush()
must not be called inside
its listeners, since it would fire the preFlush
event again, which would
result in an infinite loop.
onFlush
onFlush
is a very powerful event. It is called inside
EntityManager::flush()
after the changes to all the managed
entities and their associations have been computed. This means, the
onFlush
event has access to the sets of:
- Entities scheduled for insert
- Entities scheduled for update
- Entities scheduled for removal
- Collections scheduled for update
- Collections scheduled for removal
To make use of the onFlush
event you have to be familiar with the
internal UnitOfWork API, which grants you access to the previously
mentioned sets. See this example:
1 <?php
class FlushExampleListener
{
public function onFlush(OnFlushEventArgs $eventArgs)
{
$em = $eventArgs->getObjectManager();
$uow = $em->getUnitOfWork();
foreach ($uow->getScheduledEntityInsertions() as $entity) {
}
foreach ($uow->getScheduledEntityUpdates() as $entity) {
}
foreach ($uow->getScheduledEntityDeletions() as $entity) {
}
foreach ($uow->getScheduledCollectionDeletions() as $col) {
}
foreach ($uow->getScheduledCollectionUpdates() as $col) {
}
}
}
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The following restrictions apply to the onFlush
event:
- If you create and persist a new entity in
onFlush
, then callingEntityManager::persist()
is not enough. You have to execute an additional call to$unitOfWork->computeChangeSet($classMetadata, $entity)
. - Changing primitive fields or associations requires you to
explicitly trigger a re-computation of the changeset of the
affected entity. This can be done by calling
$unitOfWork->recomputeSingleEntityChangeSet($classMetadata, $entity)
.
postFlush
postFlush
is called at the end of EntityManager::flush()
.
EntityManager::flush()
can NOT be called safely inside its listeners.
This event is not a lifecycle callback.
preUpdate
PreUpdate is called inside the EntityManager::flush()
method,
right before an SQL UPDATE
statement. This event is not
triggered when the computed changeset is empty, nor for a DQL
UPDATE
statement.
Changes to associations of the updated entity are never allowed in this event, since Doctrine cannot guarantee to correctly handle referential integrity at this point of the flush operation. This event has a powerful feature however, it is executed with a PreUpdateEventArgs instance, which contains a reference to the computed change-set of this entity.
This means you have access to all the fields that have changed for
this entity with their old and new value. The following methods are
available on the PreUpdateEventArgs
:
getEntity()
to get access to the actual entity.getEntityChangeSet()
to get a copy of the changeset array. Changes to this returned array do not affect updating.hasChangedField($fieldName)
to check if the given field name of the current entity changed.getOldValue($fieldName)
andgetNewValue($fieldName)
to access the values of a field.setNewValue($fieldName, $value)
to change the value of a field to be updated.
A simple example for this event looks like:
1 <?php
use Doctrine\ORM\Event\PreUpdateEventArgs;
class NeverAliceOnlyBobListener
{
public function preUpdate(PreUpdateEventArgs $eventArgs)
{
if ($eventArgs->getEntity() instanceof User) {
if ($eventArgs->hasChangedField('name') && $eventArgs->getNewValue('name') == 'Alice') {
$eventArgs->setNewValue('name', 'Bob');
// The following will only work if `status` is already present in the computed changeset.
// Otherwise it will throw an InvalidArgumentException:
$eventArgs->setNewValue('status', 'active');
}
}
}
}
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You could also use this listener to implement validation of all the fields that have changed. This is more efficient than using a lifecycle callback when there are expensive validations to call:
1 <?php
use Doctrine\ORM\Event\PreUpdateEventArgs;
class ValidCreditCardListener
{
public function preUpdate(PreUpdateEventArgs $eventArgs)
{
if ($eventArgs->getEntity() instanceof Account) {
if ($eventArgs->hasChangedField('creditCard')) {
$this->validateCreditCard($eventArgs->getNewValue('creditCard'));
}
}
}
private function validateCreditCard($no)
{
// throw an exception to interrupt flush event. Transaction will be rolled back.
}
}
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Restrictions for this event:
- Changes to associations of the passed entities are not recognized by the flush operation anymore.
- Changes to fields of the passed entities are not recognized by
the flush operation anymore, use the computed change-set passed to
the event to modify primitive field values, e.g. use
$eventArgs->setNewValue($field, $value);
as in the Alice to Bob example above. - Any calls to
EntityManager::persist()
orEntityManager::remove()
, even in combination with theUnitOfWork
API are strongly discouraged and don't work as expected outside the flush operation.
postUpdate, postRemove, postPersist
These three post* events are called inside EntityManager::flush()
.
Changes in here are not relevant to the persistence in the
database, but you can use these events to alter non-persistable items,
like non-mapped fields, logging or even associated classes that are
not directly mapped by Doctrine.
- The
postUpdate
event occurs after the database update operations to entity data. It is not called for a DQLUPDATE
statement. - The
postPersist
event occurs for an entity after the entity has been made persistent. It will be invoked after all database insert operations for new entities have been performed. Generated primary key values will be available for all entities at the time this event is triggered. - The
postRemove
event occurs for an entity after the entity has been deleted. It will be invoked after all database delete operations for entity rows have been executed. This event is not called for a DQLDELETE
statement.
At the time |
The |
Making changes to entities and calling The reason is that it causes re-entrance into This may lead to entity or collection updates being missed, applied only in parts and changes being lost at the end of the commit phase. |
postLoad
The postLoad event occurs after the entity has been loaded into the current
EntityManager
from the database or after refresh()
has been applied to it.
When using |
onClear
The onClear
event occurs when the EntityManager::clear()
operation is invoked,
after all references to entities have been removed from the unit of work.
This event is not a lifecycle callback.
Entity listeners
An entity listener is a lifecycle listener class used for an entity.
- The entity listener's mapping may be applied to an entity class or mapped superclass.
- An entity listener is defined by mapping the entity class with the corresponding mapping.
Entity listeners class
An Entity Listener
could be any class, by default it should be a class with a no-arg constructor.
- Different from Implementing Event Listeners an
Entity Listener
is invoked just to the specified entity - An entity listener method receives two arguments, the entity instance and the lifecycle event.
- The callback method can be defined by naming convention or specifying a method mapping.
- When a listener mapping is not given the parser will use the naming convention to look for a matching method,
e.g. it will look for a public
preUpdate()
method if you are listening to thepreUpdate
event. - When a listener mapping is given the parser will not look for any methods using the naming convention.
To define a specific event listener method (one that does not follow the naming convention) you need to map the listener method using the event type mapping:
1 <?php
use Doctrine\ORM\Event\PostLoadEventArgs;
use Doctrine\ORM\Event\PostPersistEventArgs;
use Doctrine\ORM\Event\PostRemoveEventArgs;
use Doctrine\ORM\Event\PostUpdateEventArgs;
use Doctrine\ORM\Event\PreFlushEventArgs;
use Doctrine\ORM\Event\PrePersistEventArgs;
use Doctrine\ORM\Event\PreRemoveEventArgs;
use Doctrine\ORM\Event\PreUpdateEventArgs;
class UserListener
{
#[PrePersist]
public function prePersistHandler(User $user, PrePersistEventArgs $event): void { // ... }
#[PostPersist]
public function postPersistHandler(User $user, PostPersistEventArgs $event): void { // ... }
#[PreUpdate]
public function preUpdateHandler(User $user, PreUpdateEventArgs $event): void { // ... }
#[PostUpdate]
public function postUpdateHandler(User $user, PostUpdateEventArgs $event): void { // ... }
#[PostRemove]
public function postRemoveHandler(User $user, PostRemoveEventArgs $event): void { // ... }
#[PreRemove]
public function preRemoveHandler(User $user, PreRemoveEventArgs $event): void { // ... }
#[PreFlush]
public function preFlushHandler(User $user, PreFlushEventArgs $event): void { // ... }
#[PostLoad]
public function postLoadHandler(User $user, PostLoadEventArgs $event): void { // ... }
}
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The order of execution of multiple methods for the same event (e.g. multiple @PrePersist) is not guaranteed. |
Entity listeners resolver
Doctrine invokes the listener resolver to get the listener instance.
- A resolver allows you register a specific entity listener instance.
- You can also implement your own resolver by extending
Doctrine\ORM\Mapping\DefaultEntityListenerResolver
or implementingDoctrine\ORM\Mapping\EntityListenerResolver
Specifying an entity listener instance :
1 <?php
use Doctrine\ORM\Event\PreUpdateEventArgs;
// User.php
/** @Entity @EntityListeners({"UserListener"}) */
class User
{
// ....
}
// UserListener.php
class UserListener
{
public function __construct(MyService $service)
{
$this->service = $service;
}
public function preUpdate(User $user, PreUpdateEventArgs $event)
{
$this->service->doSomething($user);
}
}
// register a entity listener.
$listener = $container->get('user_listener');
$em->getConfiguration()->getEntityListenerResolver()->register($listener);
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Implementing your own resolver:
1 <?php
use Doctrine\ORM\Mapping\DefaultEntityListenerResolver;
class MyEntityListenerResolver extends DefaultEntityListenerResolver
{
public function __construct($container)
{
$this->container = $container;
}
public function resolve($className)
{
// resolve the service id by the given class name;
$id = 'user_listener';
return $this->container->get($id);
}
}
// Configure the listener resolver only before instantiating the EntityManager
$configurations->setEntityListenerResolver(new MyEntityListenerResolver);
$entityManager = new EntityManager(.., $configurations, ..);
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Load ClassMetadata Event
loadClassMetadata
- The loadClassMetadata
event occurs after the
mapping metadata for a class has been loaded from a mapping source
(attributes/annotations/xml/yaml) in to a Doctrine\ORM\Mapping\ClassMetadata
instance.
You can hook in to this process and manipulate the instance.
This event is not a lifecycle callback.
1 <?php
use Doctrine\ORM\Event\LoadClassMetadataEventArgs;
$test = new TestEventListener();
$evm = $em->getEventManager();
$evm->addEventListener(Doctrine\ORM\Events::loadClassMetadata, $test);
class TestEventListener
{
public function loadClassMetadata(LoadClassMetadataEventArgs $eventArgs)
{
$classMetadata = $eventArgs->getClassMetadata();
$fieldMapping = array(
'fieldName' => 'about',
'type' => 'string',
'length' => 255
);
$classMetadata->mapField($fieldMapping);
}
}
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If not class metadata can be found, an onClassMetadataNotFound
event is dispatched.
Manipulating the given event args instance
allows providing fallback metadata even when no actual metadata exists
or could be found. This event is not a lifecycle callback.
SchemaTool Events
It is possible to access the schema metadata during schema changes that are happening in Doctrine\ORM\Tools\SchemaTool
.
There are two different events where you can hook in.
postGenerateSchemaTable
This event is fired for each Doctrine\DBAL\Schema\Table
instance, after one was created and built up with the current class metadata
of an entity. It is possible to access to the current state of Doctrine\DBAL\Schema\Schema
, the current table schema
instance and class metadata.
1 <?php
use Doctrine\ORM\Tools\ToolEvents;
use Doctrine\ORM\Tools\Event\GenerateSchemaTableEventArgs;
$test = new TestEventListener();
$evm = $em->getEventManager();
$evm->addEventListener(ToolEvents::postGenerateSchemaTable, $test);
class TestEventListener
{
public function postGenerateSchemaTable(GenerateSchemaTableEventArgs $eventArgs)
{
$classMetadata = $eventArgs->getClassMetadata();
$schema = $eventArgs->getSchema();
$table = $eventArgs->getClassTable();
}
}
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postGenerateSchema
This event is fired after the schema instance was successfully built and before SQL queries are generated from the
schema information of Doctrine\DBAL\Schema\Schema
. It allows to access the full object representation of the database schema
and the EntityManager.
1 <?php
use Doctrine\ORM\Tools\ToolEvents;
use Doctrine\ORM\Tools\Event\GenerateSchemaEventArgs;
$test = new TestEventListener();
$evm = $em->getEventManager();
$evm->addEventListener(ToolEvents::postGenerateSchema, $test);
class TestEventListener
{
public function postGenerateSchema(GenerateSchemaEventArgs $eventArgs)
{
$schema = $eventArgs->getSchema();
$em = $eventArgs->getEntityManager();
}
}
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