Symfony 4 / Sonata add a filter linked to a OneToMany entity

Filters are managed in the configureDatagridFilters method

protected function configureDatagridFilters(DatagridMapper $datagridMapper)

One can add a simple filter on a title or any parameter of our entity.
The show_filter parameter allows to display it when the page loads. Combined with the value of $filters, one can specify to keep the element displayed after the filter submission.

For example, one can set the filter to be permanently displayed:

            ->add('title', null, ['show_filter' => true , 'label' => 'Titre'])

Or to display it only if it has been used

->add('enabled',null,['show_filter' =>!empty($filers['enabled']['value'])?true:null, 'label' => 'Actvé'])

For a oneToMany relationship, if your entity is correctly configured, you can simply configure as follows:

$datagridMapper->add('field', null, ['show_filter' => true , 'label' => 'nom du champs']);

Basically, there is nothing to do. But we might need to filter the values. In this case, we will use doctrine to modify the selection query for the values:

->add('slug', 'doctrine_orm_callback', ['show_filter' =>!empty($filers['slug']['value'])?true:null,  'label' => 'SEO Slug',
                'callback'  => function($queryBuilder, $alias, $field, $value)
                            $queryBuilder->andWhere($queryBuilder->expr()->like('o.slug', "'%".$value["value"]."%'"));

We might also want to make a list dynamically built by ourselves:

 ->add('liste', 'doctrine_orm_choice', array(
                'label' => 'ma liste'),
                    'choices' => array(
                        'label value1' => 'value1',
                        'label value2' => 'value2',
                    'expanded' => true,
                    'multiple' => true))

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