Hum, with no flush, nothing can happen :/

http://docs.doctrine-project.org/en/2.0.x/reference/working-with-objects.html
```It is very important to understand that only EntityManager#flush() ever causes write operations against the database to be executed. Any other methods such as EntityManager#persist($entity) or EntityManager#remove($entity) only notify the UnitOfWork to perform these operations during flush.

Not calling EntityManager#flush() will lead to all changes during that request being lost.```