Symfony: call form handleRequest but avoid entity persist

Question

I have an entity that models a search form and a form type, I use that form for searching purposes only and I don't want that entity to be modified in database, so, when I do this:

$formModelEntity = $em->getRepository('AppBundle:SearchForm')
                      ->findOneBy(array('name' => 'the_model'));
$formModelForm = $this->createForm(new SearchFormType(), $formModelEntity, array('action' => $this->generateUrl('dosearch'), 'method' => 'POST'));
$formModelForm->handleRequest($request); //or ->submit($request);
if ($formModelForm->isValid())
{
     $formInstanceEntity->setFieldsFromModel($formModelEntity);
     $em->persist($formInstanceEntity);
     $em->flush();
}

The $formModelEntity changes are persisted to database, I want to avoid this but still want to take advantage of handleRequest ability to update the entity with all POST values (for read only purposes).

Is this possible?

Answer 1

the method handleRequest Does not save the changes. it only updates the object within your method.

public function newAction(Request $request)
{
// just setup a fresh $task object (remove the dummy data)
$task = new Task();

$form = $this->createFormBuilder($task)
    ->add('task', TextType::class)
    ->add('dueDate', DateType::class)
    ->add('save', SubmitType::class, array('label' => 'Create Task'))
    ->getForm();

$form->handleRequest($request);

if ($form->isValid()) {
    // ... perform some action, such as saving the task to the database

    return $this->redirectToRoute('task_success');
}

return $this->render('default/new.html.twig', array(
    'form' => $form->createView(),
));

}

the following snippet exists at http://symfony.com/doc/current/book/forms.html

and as you can see the entity is not persisted.

You're are probably adding a persist/flush and that's what's causing the entities to be updated.

Answer 2

In symfony, you only have to persist a new entity. If you update an existing entity found by your entity manager and then flush, your entity will be updated in database even if you didn't persist it.

Edit : you can detach an entity from the entity manager before flushing it using this line of code :

$em->detach($formModelEntity);