Doctrine2 Self Reference Query -- Doesn't work - doctrine-orm

Question

$ I am trying to create following scenario with doctrine 2 query builder
SELECT
p . *
FROM
_tree p
LEFT JOIN
_tree c ON p.id = c.parent_id
AND (c.lft >= p.lft AND c.rgt <= p.rgt)
WHERE
p.id = 3
I have set following relationship self generated by Doctrine2
class Tree {
/**
* #var \Tree
*
* #ORM\ManyToOne(targetEntity="Tree")
* #ORM\JoinColumns({
* #ORM\JoinColumn(name="parent_id", referencedColumnName="id")
* })
*/
private $parent;
// other code
}
here is my repo class
_em->createQueryBuilder();
$qb->select('p')
->from('Entity\Tree', 'p')
->leftJoin('p.Entity\Tree','c', 'ON','p.id = c.parent_id');
return $qb->getQuery()->getResult();
}
}
but I couldn't get it done. It throws following errors
[Tue Oct 01 22:30:11 2013] [error] [client 127.0.0.1] PHP Fatal error:
Uncaught exception 'Doctrine\ORM\Query\QueryException' with
message 'SELECT p FROM Entity\Tree p LEFT JOIN p.Entity\Tree c ON
p.id = c.parent_id' in
/var/www/pcb_frame_work/System/Libraries/Vendors/Doctrine/ORM/Query/QueryException.php:39\nStack
trace:\n#0
/var/www/pcb_frame_work/System/Libraries/Vendors/Doctrine/ORM/Query/Parser.php(429):
Doctrine\ORM\Query\QueryException::dqlError('SELECT p FROM
E...')\n#1
/var/www/pcb_frame_work/System/Libraries/Vendors/Doctrine/ORM/Query/Parser.php(925):
Doctrine\ORM\Query\Parser->semanticalError('Class
Entity\Ed...')\n#2
/var/www/pcb_frame_work/System/Libraries/Vendors/Doctrine/ORM/Query/Parser.php(1561):
Doctrine\ORM\Query\Parser->JoinAssociationPathExpression()\n#3
/var/www/pcb_frame_work/System/Libraries/Vendors/Doctrine/ORM/Query/Parser.php(1506):
Doctrine\ORM\Query\Parser->JoinAssociationDeclaration()\n#4
/var/www/pcb_frame_work/System/Libraries/Vendors/Doctrine/ORM/Query/Parser.php(1435):
Doctrine\ORM\Query\Parser->Join()\n#5
/var/www/pcb_frame_work/System/Librari in
/var/www/pcb_frame_work/System/Libraries/Vendors/Doctrine/ORM/Query/QueryException.php
on line 49, referer:

Answer 1

I don't know if I understand you completely, but I think you have to change your ManyToOne relation to:
/**
* #var \Tree
*
* #ORM\ManyToOne(targetEntity="Tree", inversedBy="children")
* #ORM\JoinColumns({
* #ORM\JoinColumn(name="parent_id", referencedColumnName="id")
* })
*/
private $parent;
/**
* #ORM\OneToMany(targetEntity="Tree", mappedBy="parent")
*/
private $children;
That way you can access the children of a class with $Tree->children and it's parent with $Tree->parent.
More information about self referencing associations can be found here: http://docs.doctrine-project.org/en/latest/reference/association-mapping.html#one-to-many-self-referencing