Is it possible to update an entity in a similar way as below:
$data = new ATest(); // my entity
$data->id = 1; // id 1 already exists,
You can also use getReference to update an entity property by identifier without retrieving the database state.
https://www.doctrine-project.org/projects/doctrine-orm/en/2.6/reference/advanced-configuration.html#reference-proxies
This will establish a simple Proxy to work with the Entity by ID instead of instantiating a new Entity or explicitly getting the Entity from the database using find(), which can then be updated by flush.
$data = $entityManager->getReference('ATest', $id);
$data->setName('ORM Tested');
$entityManager->flush();
This is especially useful for updating the OneToMany or ManyToMany associations of an entity.
EG: $case->addTest($data);
It is generally bad practice to manually set the identifier of a new Entity, even if the intent is to update the entity. Instead it is usually best to let the EntityManager or Entity constructor establish the appropriate identifiers, such as a UUID. For this reason Doctrine will generate entities by default with the identifier as a private property with no setter method.