[Entity changeset] #symfony #doctrine

Doctrine offers very powerful API for getting entity properties that have changed. This can be achieved using Doctrine\ORM\UnitOfWork. We can call:

Doctrine\ORM\UnitOfWork::computeChangeSets() to compute all the changes that have been done to entities and collections and store these changes;
Doctrine\ORM\UnitOfWork::getEntityChangeSet($entity) to retrieve all changes to our entity object;
Doctrine\ORM\UnitOfWork::getOriginalEntityData($entity) to retrieve the original data of an entity before introduced changes.

This simple example will explain it:

// find entity
$post = $em->find('Entity\Post', 1);
// change property value
$post->setStatus(\Entity\Post::STATUS_PUBLISHED);

$uow = $em->getUnitOfWork();
// this step is required only if you are using UnitOfWork outside of listeners
$uow->computeChangeSets();
$changeset = $uow->getEntityChangeSet($post);

But what about relations? While working with Doctrine2 relations we are dealing with Doctrine\ORM\PersistentCollection which also has some useful public methods:

Doctrine\ORM\PersistentCollection::getSnapshot to return the last snapshot of the elements in the collection;
Doctrine\ORM\PersistentCollection::getDeleteDiff to return removed entities from the collection;
Doctrine\ORM\PersistentCollection::getInsertDiff to return new entities thast have been added to the collection;
Doctrine\ORM\PersistentCollection::isDirty to check whether this collection is dirty which means its state needs to be synchronized with the database.

Those methods are marked in doc as INTERNAL but have public access.

Usage:
// find entity
$post = $em->find('Entity\Post', 1);
$tag1 = $em->find('Entity\Tag', 1);
$tag2 = $em->find('Entity\Tag', 2);
 
$uow = $em->getUnitOfWork();
 
$post->addTag($tag1);
// this step is required only if you are using UnitOfWork outside of listeners
$uow->computeChangeSets();
// entities that have been added
$changeset = $post->getTags()->getInsertDiff();
 
$post->removeTag($tag2);
// this step is required only if you are using UnitOfWork outside of listeners
$uow->computeChangeSets();
// entities that have been removed
$changeset = $post->getTags()->getDeleteDiff();

Another example:

$snippet->setAuthor('Tintin'.random_int(1, 99));

// Compute all changesets
$uow->computeChangeSets();

// Or for this entity only
$uow->computeChangeSet($this->entityManager->getClassMetadata(Article::class), $snippet);

// Then get it, we have the field modified as the key which has for value
// an array with the old as first item and new value as the second item
// try it!
$changeset = $uow->getEntityChangeSet($snippet);

// And what is the state of this entity?
switch ($uow->getEntityState($snippet)) {
    case UnitOfWork::STATE_MANAGED:
        echo 'Snippet is managed (already in DB).';
        break;
    case UnitOfWork::STATE_REMOVED:
        echo 'Snippet is going to be removed.';
        break;
    case UnitOfWork::STATE_DETACHED:
        echo 'Snippet is detached.';
        break;
    case UnitOfWork::STATE_NEW:
        echo 'Snippet is new.';
        break;
}

Source: http://kamiladryjanek.com/doctrine2-entity-changeset-for-relations/

reanim8ed/sample.md