Doctrine Custom ID with auto increment - entity-framework

Question

I want to define some id with prefix.
For example, for one order entity its : "OR17000001"
In this example, the prefix is "OR17"
So i have declare my id entities like this :
/**
* #var string
*
* #ORM\Column(name="id", type="string", length=8)
* #ORM\Id
* #ORM\GeneratedValue(strategy="CUSTOM")
* #ORM\CustomIdGenerator(class="My\Bundle\Generator\OrderCodeGenerator")
*/
private $id;
And my Generator is :
<?php
namespace My\Bundle\Generator;
use Doctrine\ORM\Id\AbstractIdGenerator;
use Doctrine\ORM\EntityManager;
use My\Bundle\Entity\Order;
class OrderCodeGenerator extends AbstractIdGenerator
{
/**
* Format :
* $prefix - string
* $year - take 2 first letters (17)
* $increment - Take the last code + 1
*
* #param EntityManager $em
* #param \Doctrine\ORM\Mapping\Entity $entity
* #return bool|string
*/
public function generate(EntityManager $em, $entity)
{
if ($entity instanceof Order) {
$now = new \DateTime();
$year = $now->format('y');
$prefix = 'OR';
$maxCode = $em->getRepository('MyRepo:Order')->findMaxCode($year, $prefix);
if ($maxCode) {
$increment = substr($maxCode[1], -4);
$increment = (int)$increment + 1;
} else
$increment = 0;
$code = $prefix . $year . sprintf('%04d', $increment);
return $code;
}
return false;
}
}
Without forget the method findMaxCode :
public function findMaxCode($year, $prefix)
{
$qb = $this->createQueryBuilder('entity');
$qb->where($qb->expr()->like('entity.id', ':code'))
->setParameter('code', '%' . $prefix . $year . '%');
$qb->select($qb->expr()->max('entity.id'));
return $qb->getQuery()->getOneOrNullResult();
}
That's work fine =)
My problem is when i try to add some entities in same time.
My case is :
Order entity with some items (its a form collection)
Item entity
So i need to custom id of Items Order with this strategy. And the problem is for found the max code. I have this error :
SQLSTATE[23000]: Integrity constraint violation: 1062 Duplicata du
champ 'IT170000001' pour la clef 'PRIMARY'
The generator can't found the max code for generate the second item, because there is no flush.
How can i save the increment value between 2 id generation before the flush ??
Solution :
I keep numeric id for my Item. Its useful for my Order entity, its more readable than an simple int. But i don't care for Item.
Thx to Honza Rydrych

Answer 1

Querying DB for last inserted ID and then inserting "+one" isn't reliable solution.
My solution for this case would be let doctrine generate ID's by the standard way and add the prefix "OR/Year/" when you need to present the data.
(Optionaly you can write custom Twig extension for presenting the ID http://symfony.com/doc/current/templating/twig_extension.html)