Elegant way to walk backward through OneToOne table entities with Doctrine - php

Question

I have a very simply structured entity that contains a simple association
Database_Entity_Tenant
id (primary key)
parentId (id of the parent entry)
code (a simple identifier for the tenant, unique)
I defined parentId in my entity accordingly:
/**
* #Column(type="integer")
* #OneToOne(targetEntity="Tenant")
* #JoinColumn(name="parentTenantId", referencedColumnName="id")
* **/
protected $parentId;
This works fine - the generated database schema resembles my choices and its good.
Now i am writing my first method which basically has to return an array of all the tenants that are chained together, in reverse order (i use this for walking backward through a chain of tenants).
In order to do that i came up with the idea to use a while() loop.
$currentTenant = {DATABASE_ENTITY_TENANT}; // In my real code i fetch the entity object of the current tenant
$chain[] = $currentTenant;
$repository = Database::entityManager()->getRepository('Database_Entity_Tenant');
while(!$currentTenant->getParentId()){
$currentTenant = $repository->findOneBy(array(
'id' => $currentTenant->getParentId()
));
$chain[] = $currentTenant;
}
Any tenant that has no parent (such as the base tenant) will have no parent id (or null), so that would end the while loop.
Now all this may work, but it seems really rough to me. I am fairly new to Doctrine so i don't know much about it but i am sure there is some way to do this more elegantly.
QUESTION
Does Doctrine 2 provide me with any set of functions i could use to solve the above problem in a better way?
If not, then is there any other way to do this more elegantly?

Answer 1

If I'm not getting your problem wrong, you just need to find all the entries in your association table ordered by the parentId. In Doctrine2 you can do the following:
$currentTenant = {DATABASE_ENTITY_TENANT}; // assuming a valid entity
$repository = Database::entityManager()
->getRepository('Database_Entity_Tenant')
->createQueryBuilder('t')
->where('t.parentId IS NOT NULL')
->andWhere('t.parentId < :current') /* < or > */
->setParameter('current', $currentTenant->getParentId()->getId())
->orderBy('t.parentId', 'ASC') /* ASC or DESC, no array_reverse */
->getQuery()
->getResult();
/* At this point $repository contains all what you need because of Doctrine,
* but if you want a chain variable: */
$chain = array();
foreach ($repository as $tenant) {
$chain[] = $tenant->getCode(); // your tenant entity if your entity is mapped correctly
}
Hope this helps!