父子关系的实施

Question

我正在尝试实施以下内容

1个约会可以有0到多个子约会

subappointment有1个父约会

这是我尝试过的：

private Appointment parentAppointment;

@ManyToMany(cascade = CascadeType.ALL )
private List<Appointment> childrenAppointments;

我也尝试了一些JoinColumn注释，但它没有用。

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编辑：

我尝试过Pace的解决方案 - ＆gt;

@ManyToOne
private Appointment parentAppointment;

@OneToMany(cascade = CascadeType.ALL, mappedBy="parentAppointment")
private List<Appointment> childrenAppointments;

现在我遇到了这个错误： ERROR: column "appointment_id" appears twice in primary key constraint

it（Play！Framework）尝试使用此脚本创建表：

create table appointment_appointment (
appointment_id                 integer not null,
appointment_id                 integer not null,
constraint pk_appointment_appointment primary key (appointment_id, appointment_id))
;

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EDIT2：

修正：

    @ManyToOne
@JoinColumn(name = "parent_appointment")
private Appointment parentAppointment;

@OneToMany( mappedBy="parentAppointment", cascade = CascadeType.ALL)
private List<Appointment> childrenAppointments;

和

    public void setParentAppointment(Appointment ap){
    this.parentAppointment = ap;
}
public void addChildAppointment(Appointment ap){
    this.childrenAppointments.add(ap);
}

Answer 1

如果没有更多关于什么不起作用的细节，那么我无能为力。正确的注释，我是这样做的，这与标准的关系是：

@ManyToOne
private Appointment parentAppointment;

@OneToMany(cascade = CascadeType.ALL, mappedBy="parentAppointment")
private List<Appointment> childrenAppointments;

由于子约会只有1个父级，因此这将是一对多而不是多对多。在数据库中，上述设置将在约会表上为父约会创建单个列。对于没有父级的约会，此列可以为null。