为什么 Sonata Datagrid 选择默认选择空值选项

如何解决为什么 Sonata Datagrid 选择默认选择空值选项

为什么 Sonata Datagrid 选择默认选择空值选项。

->add('status',StringFilter::class,array(
            'show_filter' => true,'field_type' => ChoiceType::class,'field_options' => array(
                'required' => false,'choices' =>
                    [
                    'OK (1)' => Application::STATUS_OK,'Not eligible (-1)' => Application::STATUS_NOT_ELIGIBLE,'Problem (-2)' => Application::STATUS_PROBLEM,'Critical (-3)' => Application::STATUS_CRITICAL,'Phone Called (-4)' => Application::STATUS_CALL,'Not received phone (-5)' => Application::STATUS_NOT_RECEIVED,'Appeared (-6)' => Application::STATUS_APPEARED,'Special (-9)' => Application::STATUS_SPECIAL,'Unverified' => Null,]
            )
        ))

结果： Click here for the above code result

我不想选择默认的空值。