Doctrine DQL, class table inheritance and access to subclass fields

Question

I have a problem with a DQL query and entity specialization.

I have an Entity called Auction, which is OneToOne relation with Item

Answer 1

You can easily solve this by left-joining your base entity with your inheritance class using the id:

SELECT a FROM Entities\Auction a
    INNER JOIN a.item i 
    INNER JOIN Entities\Book b WITH b.id = i.id 
    INNER JOIN b.bookTypes bt
    WHERE bt.type = 'Fantasy' 
    AND...

or with a queryBuilder:

$queryBuilderb->select('a')
   ->from('Entities\Auction', 'a')
   ->innerJoin('a.item', 'i')
   ->innerJoin('Entities\Book', 'b', 'WITH', 'b.id = i.id')
   ->innerJoin('b.bookTypes', 'bt')
   ->where('bt.type = :type')
   ->andWhere(...
   ->setParameter('type', 'Fantasy');

This is based on the answer given by Ian Philips in the question here