Symfony2 DateTime null accept - symfony

Question

So, I want to be able send a null option to my DOB field.
Here is my form builder:
->add('birthDate', DateType::class, array(
'widget' => 'single_text',
'format' => 'yyyy-MM-dd'))
And here is those field in my entity
/**
* #ORM\Column(
* type="date",
* nullable=true
* )
* #JMS\Groups("single")
*
* #var \DateTime
*/
protected $birthDate;
When I`m trying to send a null I got an error msg
Expected argument of type "DateTime", "NULL" given
any ideas?
CRITICAL - Uncaught PHP Exception Symfony\Component\PropertyAccess\Exception\InvalidArgumentException: "Expected argument of type "DateTime", "NULL" given" at /var/www/server.local/vendor/symfony/symfony/src/Symfony/Component/PropertyAccess/PropertyAccessor.php line 253
$type = $trace[$i]['args'][0];
$type = is_object($type) ? get_class($type) : gettype($type);
throw new InvalidArgumentException(sprintf('Expected argument of type "%s", "%s" given', substr($message, $pos, strpos($message, ',', $pos) - $pos), $type));
}
}

Answer 1

In this case, the problem was caused by PHP type hinting.
If you use type hinting (for instance setBirthDate(\DateTime $value)) then PHP forces you that you actually provide a DateTime object. Obviously, null is not such an object. To resolve this problem, it is possible to give $value a default value like this: setBirthDate(\DateTime $value = null).
This is documented behavior and explained in the PHP Documentation (http://php.net/manual/en/functions.arguments.php#functions.arguments.type-declaration).
Relevant passage:
To specify a type declaration, the type name should be added before the parameter name. The declaration can be made to accept NULL values if the default value of the parameter is set to NULL.

Answer 2

The problem occurs due type-hinted setter as it is mentioned in the comments. There are two solutions:
1. Use 'by_reference' => true on your form:
$builder->add(
'birthDate',
DateType::class,
[
'widget' => 'single_text',
'format' => 'yyyy-MM-dd',
'by_reference' => true,
]
);
2. Let your setter accept null:
public function setBirthDate(\DateTime $value = null)
{
.....
}

Answer 3

Don't pass any values to it. Make the field not required by doing this:
->add(
'birthDate',
DateType::class,
array(
'required' => false,
'widget' => 'single_text',
'format' => 'yyyy-MM-dd'
)
)

Answer 4

I have been using DOB field in my project. Try this.
My ORM file looks like this <field name="dob" type="date" column="dob" nullable="true"/>
->add('dob','birthday',array(
'widget' => 'single_text',
'format' => 'dd-MM-yyyy',
'required' => false,
'attr' => array('class' => 'datepicker',
'data-provide' => 'datepicker','data-date-format' => 'dd-mm-yyyy')
))