How to specify the NULL field type in the Model entity?

Question

symfony

I'm developing on Symfony 2.
There are Entity and Model folders.
In entity it is clear how to make the NULL field.
How to do it in Model?
All fields are listed as

@var string
protected $foo

@var integer
protected $bar

Answer 1

Understood. In Entity null is written like this:

/**
     * @ORM\Column(nullable=true)
     */
    protected $string;

And in Model it is written in a separate file, which is located in the Resources / config folder