datepicker posts now() even if empty ZF2 Doctrine2 - doctrine-orm

Question

I have a form with two dates where I use bootstrap3 datepicker. The dates are not mandatory. When I submit the form and one or both of the dates are not filled out, the posted entity contains the actual datetime instead of beeing NULL. When I check the $_POST the dates are NULL.
I use doctrine2 and ZF2. Maybe you need more informations... Thanks in advance for any help.

Answer 1

Solution for me was to add filter Zend\Filter\Null to the form element so that empty strings were converted to NULL.
array(
'name' => 'Zend\Filter\Null',
'options' => array(
'type' => 'string',
),
),
Cause of the problem:
If your form is set to BindOnValidate then a hydrator will be used, which can manipulate the values. It converts strings to DateTime objects if the entity property is a DateTime. Test this using
$form->setBindOnValidate(false);
Which should mean that your value remains an empty string '' immediately after calling isValid().
I found that DoctrineObject hydrator->handleTypeConversions() was converting any string (e.g. from my form POST) into a DateTime object for consistency with the entity field. An empty string results in a DateTime representing time() i.e. current time.
When I intercepted the form POST and converted empty string '' to null, the hydrator left that field as null.
I'm not sure whether it is best to manipulate the POST data within the controller before validation, or to modify the hydration strategy but I presumably either could work?
EDIT: I tried adding a custom strategy to the DoctrineObject hydrator to convert empty string '' to NULL but the DoctrineObject does not trigger the custom strategy, it does the type conversion irrespective.
Copy of the DoctrineObject hydrator code that was making the change:
protected function handleTypeConversions($value, $typeOfField)
{
switch($typeOfField) {
case 'datetime':
case 'time':
case 'date':
if (is_int($value)) {
$dateTime = new DateTime();
$dateTime->setTimestamp($value);
$value = $dateTime;
} elseif (is_string($value)) {
$value = new DateTime($value);
}
break;
default:
}
return $value;
}

Answer 2

You should define the date fields with a default value of NULL and then add the nullable=true option.
/**
* #ORM\Column(type="date", nullable=true)
*/
private $someDateField= null;
Take a look at the documentation for more details.

Answer 3

I discovered something new:
In my controller, the $form->isValid() function is the cause that the date fields are populated with the current date time.
I wrote out the fields values just BEFORE the isValid() and they were NULL as expected, because not filled out in the form.
I wrote out the fields values just AFTER the isValid() and they were NOT NULL, but an object.
The code is quite simple:
if ($form->isValid()) {
$objectManager->persist($group);
$objectManager->flush();
}
I really don't know ghow to solve this...