How to handle date format in symfony2 with doctrine?

Validation is a very common task in web applications. Data entered in forms needs to be validated and it needs to be validated before it is written into a database or passed to a web service. Symfony makes easy to validate form by its validation component.

Date format and validation message can also handle in form type class of any entity as in following code.

public function buildForm(FormBuilderInterface $builder, array $options)
    {
        $builder
                ->add('firstName')
                ->add('middleName')
                ->add('lastName')
                ->add('birthDate', 'date', array(
                    'widget' => 'single_text',
                    'format' => 'yyyy-MM-dd', 
                    'invalid_message' => 'Invalid date format.',
                    ))
                ->add('gender')
        ;
    }