Unmapped Form Fields in Symfony

Objective

Use a form class to build out a form to edit an entity.

Add fields to the form to control navigation after submitting the form, for example.

These extra fields don't have equivalents in the entity class. It cannot be used to inspect their values in the submitted form data.

Form Class

• The first two form fields added to the form builder correspond to properties of the entity class.
• The next field does not correspond to an entity class property.
  • mapped => false marks this as an unmapped field.
  • The field type is next_nav_choice.
    • This is a custom field type that extends choice without any extra functionality.
    • It is simply a hook to differentiate this set of radio buttons from other ones in the front-end template, since these are always going to represent navigation choices.
  • placeholder => null removes an option inserted by Symfony that explicitly sets the choice to "no choice".
  • empty_data marks the value that will be submitted if none of the choices in the form are selected.
  • expanded => true causes the "choice" field type to be rendered as a list of radio buttons.

class InvoiceType extends AbstractType 
{
	public function buildForm(FormBuilderInterface $builder, array $options) 
	{
		$builder
			->add('number', 'integer', array(
				'label' => 'Invoice Number',
			))
			->add('amount', 'money', array(
				'currency'=> 'USD',
			))
			// ...
			->add('next', 'next_nav_choice', array(
				'label' => 'After saving the invoice go to:',
				'placeholder' => null,
				'required' => false,
				'choices' => array(
					'list' => 'invoice listings',
					'details' => 'view the invoice',
					'add' => 'add another invoice',
					),
				'empty_data' => array('list'),
				'expanded' => true,
				'mapped' => false,
			))
			->add('save', 'submit');
	}

Accessing the unmapped field value in the controller

The field value can be accessed with $form->get('next')->getData();

N.B. From the documentation it seems like the empty_data setting should represent a default value for the the list of options, but this doesn't work.

Setting a default value for unmapped fields

$form->get('next')->setData($next);