Convert data before saving to database - symfony

Question

Just getting started with Symfony, so please bear with me here.
I have an Entity with a field "myField" that is stored in the database as an ENUM with values 'Y' or 'N'. (This is an old DB schema that I'm working with and trying to use symfony as an app to manipulate the data).
I want to represent "myField" with a checkbox for on or off (0 or 1). When the form is saved, how would I transform the value to the appropriate 'Y' or 'N' value before persisting it to the database?
I looked at Data Transformers, and that may be where I need to go, but it seems so silly to create a new class and file just to convert that data. This is a very simple transformation.
Maybe instead I would just change the setMyField($myField) () {} setter method on the Entity to convert the data there? And likewise, convert it back in getMyField() {}? But doesn't Doctrine also use the setter methods? If so, then when Doctrine set a value, it would be the proper value (0 or 1) from the database and wouldn't need transforming. But if the form set the value, it would need transforming.
Here's the action code:
public function newAction(Request $request)
{
$course = new Course();
$form = $this->createForm(new CourseForm(), $course);
$form->handleRequest($request);
if ($form->isValid()) {
$em = $this->getDoctrine()->getManager();
$em->persist($course);
$em->flush();
return $this->redirect($this->generateUrl('courses'));
}
return $this->render('PucsTestBundle:Course:new.html.twig', array(
'form' => $form->createView(),
));
}
I think I could convert the data myself in the controller just before I call handleRequest, but that is probably not good practice.
Additionally, I have a field in the database "days" that is just a VARCHAR that would be something like MTW for Monday, Tuesday Wednesday. I want to present a checkbox for all these values, and then post-process the form submission to convert the data to the appropriate single value.

Answer 1

You should use a custom Doctrine Type as defined here in the documentation
<?php
namespace My\Project\Types;
use Doctrine\DBAL\Types\Type;
use Doctrine\DBAL\Platforms\AbstractPlatform;
/**
* My custom datatype.
*/
class OldBooleanType extends Type
{
const NAME = 'OldBoolean'; // modify to match your type name
public function getSQLDeclaration(array $fieldDeclaration, AbstractPlatform $platform)
{
return 'OldBoolean';
}
public function convertToPHPValue($value, AbstractPlatform $platform)
{
if ($value === 'Y'){
return true;
}
if ($value === 'N'){
return false;
}
return null;
}
public function convertToDatabaseValue($value, AbstractPlatform $platform)
{
if ($value === true){
return 'Y';
}
if ($value === false){
return 'N';
}
return null;
}
public function getName()
{
return self::NAME;
}
}

Answer 2

From Symfony documentation: http://symfony.com/doc/current/cookbook/form/data_transformers.html
Data transformers are used to translate the data for a field into a format that can be displayed in a form (and back on submit).