@OnetoMany 类调用

Question

我的课程需要一些帮助...

package com.it.ese.orbit.entity;
import javax.persistence.*;
import java.util.List;



/**
 * Created by IntelliJ IDEA.
 * User: Shahriar Newaz
 * Date: 07/03/11
 * Time: 10.07
 */
@Entity
@Inheritance(strategy =InheritanceType.JOINED)
public class OrbitObject {
    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue


    @Column(name="id",nullable = false)
    private Long id;

    @Column(name="Scenario",nullable = false)
    private String scenario;  // not sure about how to map scenario

    @Column(name="code",nullable = true)
    private String code;

    @Column(name="name",nullable = true)
    private String name;

    @OneToOne(cascade=CascadeType.ALL)
    private Bia bia;

    @OneToOne(cascade=CascadeType.ALL)
    public Impatti impatti;


    @Column(name="parent",nullable = true)
    @OneToMany(cascade=CascadeType.ALL)
    private OrbitObject OrbitObject;


    public Long getId() {
     return id;
    }

    protected void setId(Long id) {
     this.id = id;
    }

    public String getCode() {
     return code;
    }

    public void setCode(String code) {
     this.code = code;
    }



    public String getScenario() {
        return scenario;
    }
    public void setScenario(String scenario) {
        this.scenario = scenario;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        name = name;
    }

     // LOG
    @Override
    public String toString(){
        return "com.it.ese.orbit.models.OrbitObject["
        + " - name="+name + " - scenario="+scenario +" - id= "+id+"]";
    }
}

但我收到这个错误...

原因：org.hibernate.AnnotationException：非法尝试将非集合映射为 @OneToMany、@ManyToMany 或 @CollectionOfElements：com.it.ese.orbit.entity.OrbitObject.OrbitObject

我希望创建一个 OrbitObject 字段，就像同一类的对象... 请帮忙！

Answer 1

您要么执行

@Column(name="parent",nullable = true)
@ManyToOne(cascade=CascadeType.ALL)
private OrbitObject OrbitObject;

要么

@Column(name="parent",nullable = true)
@OneToMany(cascade=CascadeType.ALL)
private Set<OrbitObject> OrbitObject;

第一种情况意味着该实体将是拥有方，即它将拥有外键。

Answer 2

OneToMany 意味着 OrbitObject 有许多 OrbitObject 子级，但事实并非如此，因为 OrbitObject 属性不是集合。
您必须将其转换为 ManyToOne

Answer 3

例如，您可以使用 @OneToMany 来引用元素集合

@OneToMany
List<OrbitObject> orbitList;