Symfony: Form issue using Return type hinting in Doctrine Entity methods

Question

I was being exceptionally diligent today and decided to return-type hint all of my symfony entity methods. So:

<?php

Class User {
    private string $username;
    public method getUsername(): string {}
}

all good and well, until I made a form to create a new user:

$user = new User();
$this->createForm(SignupType::class, $user);

when the form is displayed, Symfony automatically gets the properties of this new instance of User $user . But since it is a new instantiation, its username property is of course still null , which is an incorrect return type as it needs to be string .

Should I either:

1. have no return-type hinting in Symfony entities (meh);
2. set $username = '' (but hat kind of defeats the purpose of not allowing blanks and I can see all sorts of errors evolving); or
3. unmap the field on the symfony form
4. other possible solutions...

Answer 1

If an Entity Property cannot be null ( and you use PHP 7.1+ ), then applying the nullable return type declaration sounds more like a dirty and fast workaround to maintain a direct data binding between Entities and Forms ( using the Symfony Form Component ).

A better global approach ( in my opinion ) is to decouple the Form data binding from your Doctrine Entities using a DTO ( Data Transfer Object ), that is a simple POPO ( Plain Old PHP Object ) to contain your form data.

Using a DTO will allow you to maintain a strict type hinting in your Doctrine Entities ( no loss of data consistency ) and will decouple Form data binding ( but also data validation ) from your Entities.

DTO's allows reusability and have many other advantages.

Some useful references about the use of DTO's with Symfony Forms:

• Avoiding Entities in Forms ( by Iltar van der Berg )
• Rethinking Form Development ( by Iltar van der Berg )
• Symfony Forms 101 ( by Bernhard Schussek the creator of the Form component )
• Don't Use Entities in Symfony Forms. Use Custom Data Objects Instead
• Entities should always be valid

Answer 2

If you're using PHP 7.0, which has no nullable return type declaration support, the first option will be the right (non-hacky) choice. In case of you're using PHP 7.1+, you can define a nullable return type declaration .

<?php

class User 
{
    public function getUsername(): ?string {}
}