CheckboxListMapper example

/** * @return void */
    public function buildForm(FormBuilderInterface $builder, array $options)
    {
        $unknownValues = [];
        $choiceList = $this->createChoiceList($options);
        $builder->setAttribute('choice_list', $choiceList);

        if ($options['expanded']) {
            $builder->setDataMapper($options['multiple'] ? new CheckboxListMapper() : new RadioListMapper());

            // Initialize all choices before doing the index check below.             // This helps in cases where index checks are optimized for non             // initialized choice lists. For example, when using an SQL driver,             // the index check would read in one SQL query and the initialization             // requires another SQL query. When the initialization is done first,             // one SQL query is sufficient.
            $choiceListView = $this->createChoiceListView($choiceList, $options);
            $builder->setAttribute('choice_list_view', $choiceListView);