How to set default value for form field in Symfony2?

Question

Is there an easy way to set a default value for text form field?

Answer 1

A general solution for any case/approach, mainly by using a form without a class or when we need access to any services to set the default value:

// src/Form/Extension/DefaultFormTypeExtension.php

class DefaultFormTypeExtension extends AbstractTypeExtension
{
    public function buildForm(FormBuilderInterface $builder, array $options)
    {
        if (null !== $options['default']) {
            $builder->addEventListener(
                FormEvents::PRE_SET_DATA,
                function (FormEvent $event) use ($options) {
                    if (null === $event->getData()) {
                        $event->setData($options['default']);
                    }
                }
            );
        }
    }

    public function configureOptions(OptionsResolver $resolver)
    {
        $resolver->setDefault('default', null);
    }

    public function getExtendedType()
    {
        return FormType::class;
    }
}

and register the form extension:

app.form_type_extension:
    class: App\Form\Extension\DefaultFormTypeExtension
    tags:
        - { name: form.type_extension, extended_type: Symfony\Component\Form\Extension\Core\Type\FormType }

After that, we can use default option in any form field:

$formBuilder->add('user', null, array('default' => $this->getUser()));
$formBuilder->add('foo', null, array('default' => 'bar'));