gistfile1.php

<?php

// generation filter
$builder->add('generation_name', 'entity', array(
    'class' => 'AramisSpsCoreBundle:VehicleModelGeneration',
    'property' => 'name_lc',
    'query_builder' => function(EntityRepository $er) use($this) {
            return $er->createQueryBuilder('vmg');
                ->where('vmg.vehicleModel = ' . $this->vehicleModelId)
                ->orderBy('vmg.name', 'ASC');
        },
    'expanded' => false, 
    'label'    => 'Génération',
    'multiple' => true,
    'required' => false,
));