ride.php

<?php 

->add('ride', 'filter_collection_adapter', array(
                'type' => new BookingOptionalRideToFilterType(),
                'label' => 'Corsa',
                'add_shared' => function (FilterBuilderExecuterInterface $qbe)  {
                    $closure = function (QueryBuilder $filterBuilder, $alias, $joinAlias, Expr $expr) {
                        $filterBuilder->leftJoin('AppBundle:RideSelector', 'rideSelector', 'WITH', 'rideSelector.object_class = \'AppBundle\Entity\BookingOptional\'');
                        $filterBuilder->leftJoin('AppBundle:Ride', 'ride', 'WITH', 'ride.id IN (rideSelector.ride_tags)');
                    };

                    // then use the query builder executor to define the join, the join's alias and things to do on the doctrine query builder.
                    $qbe->addOnce($qbe->getAlias().'.ride', 'ride', $closure);
                },
            ))