Validate embed form if not empty - symfony

Question

I have two entities: Program and Widget
Program
class Program
{
....
/**
* #Assert\Valid
*
* #ORM\OneToOne(targetEntity="Widget", inversedBy="program", cascade={"persist", "remove"}, orphanRemoval=true)
* #ORM\JoinColumn(nullable=true)
*/
private $widget;
}
Widget
class Widget
{
/**
* #ORM\Id()
* #ORM\GeneratedValue()
* #ORM\Column(type="integer")
*/
private $id;
/**
* #ORM\Column(type="integer")
*/
private $addressId;
/**
* #ORM\Column(type="integer")
*/
private $extAddressId;
/**
* #ORM\Column(type="string")
*/
private $language;
/**
* #ORM\OneToOne(targetEntity="Program", mappedBy="widget")
*/
private $program;
}
I have two issues.
First I need to add a conditional constraint on Widget, addressId or extAddressId have te be defined, not both.
Second widget is not required for Program. It's either you let all form fields blank, like you don't want to add a widget to the form OR you fill the form but you have to respect the conditional constraint and of course the required fields.
I was trying to add a Callback as it's explained in the official doc here but I have no idea how to combine both.

Answer 1

First you have to define Assert von widget relation, like
Column Widet
#Assert\Valid()
As next, you have to work with expressions on the widget itself, like
Column adressId
#Assert\Expression(
* expression=" (this.getAdressId() and !this.extAdressId()) or !this.getAdressId() ",
* message="error.cant_be_enabled_with_adress_id"
* )
Column extAdressId
#Assert\Expression(
* expression=" (this.getExtAddressId() and !this.getAdressId()) or !this.getExtAdressId() ",
* message="error.cant_be_enabled_with_adress_id"
* )