Symfony2 and Doctrine - Error: Invalid PathExpression. Must be a StateFieldPathExpression

Question

I have an entity that looks like this:

/**
 * @Gedmo\\Tree(type=\"nested\")
 * @ORM\\Table(name=\"categories\")
 * @ORM\\Entity()
 */
class Category extends          


        

Answer 1

Solution using createQueryBuilder:

$query->SELECT('pa.id')
        ->from('Category', 'ca');
$query->join('ca.parent', 'pa');

$result = $query->getQuery()->getArrayResult();

Answer 2

You can use the currently undocumented IDENTITY function to select the FK IDs in a query:

SELECT IDENTITY(c.parent) ...

Answer 3

You are selecting an object that is not joined. Like said in another answer, you have to do something like :

qb->innerJoin("c.parent", "p")