How to properly inherit and connect classes?

Question

PHP

Guys, I can't figure it out.
I have three classes.
1) User (methods: create, update, delete) in mysql for users is a separate table.
2) Organization (methods: create, update, delete) in mysql for organizations is also a separate table.
3) Invoice (accounts) (methods: create, update, delete) in mysql for accounts a separate table, but contains id_user and id_org.
It turns out that my third Invoice class will crash if I rename some column in the tables users or organizations.
Did I select the entities incorrectly, or what is the reason?

Answer 1

Your Invoice should depend on User and Organization objects. Accordingly, inside Invoice you work with the parameters of the transferred objects.

$uid = $this->User->getId();
    $oid = $this->Organisation->getId();

They must be passed in the constructor or as separate methods. Code without comments, well, the editor is not very convenient here.

class Invoice
{
    protected $User;
    protected $Organisation;

    public function __construct(User $User = null, Organisation $Organisation = null)
    {
        if (!is_null($User)) {
            $this->setUser($User);
        }
        if (!is_null($Organisation)) {
            $this->setOrganisation($Organisation);
        }
    }
    public function setUser(User $User)
    {
        $this->User = $User;
    }
    public function setOrganisation(Organisation $Organisation)
    {
        $this->Organisation = $Organisation;
    }
}

This approach will help you get additional fields of the User and Organization objects and not worry that you will change the table.