我如何转换为JSON学说关联ArrayCollection

Question

我有以下关联

 return this.httpClient
  .put<T>(`${this.url}/${this.endpoint}`, JSON.stringify(item), {
    headers: this.addHeaders()
  })
  .subscribe(data => this.serializer.fromJson(data) as T);

当我选择一个具有某些UserNote的用户时，上面的关联会产生以下objetc：

class User
{
....
/**
 * @OneToMany(targetEntity="UserNote", mappedBy="user", fetch="EAGER")
 */
public $userNote;
....
}
class UserNote implements
{
 ....
/**
 * @ManyToOne(targetEntity="User", inversedBy="userNote")
 * @JoinColumn(name="id_user", referencedColumnName="id_user")
 */
public $user;
....
}

因此，当我使用json_encode时，我得到以下结果：

App\Models\Entity\User Object
(
[id] => 4
[name] => Filipe Rodrigues
[email] => filipe@email.com.br
[login] => master
[password] => *********
[date] => DateTime Object
    (
        [date] => 2016-05-04 00:00:00.000000
        [timezone_type] => 3
        [timezone] => UTC
    )

[lastLogin] => DateTime Object
    (
        [date] => 2017-08-09 11:45:38.000000
        [timezone_type] => 3
        [timezone] => UTC
    )

[numLogin] => 161
[fone1] => 1112345678
[fone2] => 
[cep] => 09112000
[adress] => Rua Sila NAlon Gonzzaga
[cpf] => 289.233.498-52
[typeUser] => 3
[facebook] => 
[site] => 
[plan] => 
[idPlan] => 1
[note] => 
[fl_vip] => 
[fl_trial] => 0
[fl_cob] => 0
[recorrenceCode] => 0566AEA4DADA9861147E5F95DD2AF24B
[billingDay] => 13
[status] => 8
[token] => 
[parent] => 
[userNote] => Doctrine\ORM\PersistentCollection Object
    (
        [snapshot:Doctrine\ORM\PersistentCollection:private] => Array
            (
                [0] => App\Models\Entity\UserNote Object
                    (
                        [id] => 1
                        [note] => teste
                        [date] => DateTime Object
                            (
                                [date] => 2018-01-02 00:00:00.000000
                                [timezone_type] => 3
                                [timezone] => UTC
                            )

                        [user] => App\Models\Entity\User Object
 *RECURSION*
                    )

            )
......

userNote没有转换，如何使用json_encode转换教义关联？

有人可以帮助我吗？