Doctrine Unidirectional Association Sample 1

User.php

<?php

namespace System\Entity;

use Doctrine\ORM\Mapping as ORM;

/**
 * Class User
 * @package System\Entity
 * @ORM\Entity()
 * @ORM\Table(name="`user`")
 */
class User
{
    /**
     * @ORM\Id()
     * @ORM\GeneratedValue(strategy="AUTO")     
     * @ORM\Column(name="id", type="bigint", options={"unsigned":true})
     */
    private $id;
    
    ...
}

UserInformation.php

<?php

namespace System\Entity;

use Doctrine\ORM\Mapping as ORM;

/**
 * Class UserInformation
 * @package System\Entity
 * @ORM\Entity()
 * @ORM\Table(name="`user_information`")
 */
class UserInformation
{
    /**
     * @ORM\Id()
     * @ORM\OneToOne(targetEntity="System\Entity\User")
     * @ORM\JoinColumn(name="user_id", referencedColumnName="id")
     */
    private $user;
    
    ...
}