JPA OneToMany坚持孩子

Question

我使用Spring Boot JPA，如何使用OneToMany关系来保持孩子？ 在创建父项时，似乎子实体不会自动持久化。

其他关系它运作正常，为什么？

注册实体：

@Entity
@Table(name="Registration")
public class Registration implements Serializable {
    @Id
    @GeneratedValue(generator = "uuid")
    @GenericGenerator(name="uuid", strategy = "uuid2")
    @Column(columnDefinition = "BINARY(16)")
    private UUID uuid;

    @OneToMany(mappedBy ="registration", cascade = CascadeType.ALL, fetch = FetchType.LAZY)
    @JoinColumn(name="registration", nullable = false)
    private List<Payment> payment;

    private DateTime created;
    private DateTime updated;
}

付款实体：

@Entity
@Table(name="Payment")
public class Payment {
    @Id
    @GeneratedValue(generator = "uuid")
    @GenericGenerator(name="uuid", strategy = "uuid2")
    @Column(columnDefinition = "BINARY(16)")
    private UUID uuid;

    /* @ManyToOne(targetEntity=Registration.class)
    @JoinColumn(name="registration")
    private Registration registration; */

    private DateTime created;
    private DateTime updated;
}

尝试创建注册时记录：

  

com.mysql.jdbc.exceptions.jdbc4.MySQLIntegrityConstraintViolationException：“created”列不能为null