Question

我不理解如何做一些可能很容易做的事情。我有一个名为＆＃34; Composer＆＃34;的表。 A＆＃34;作曲家＆＃34;可以有很多作品（＆＃34;作曲＆＃34;表）。当我通过Spring Boot运行时出现以下错误：

19:11:40 web.1  | Caused by: org.hibernate.AnnotationException: 
mappedBy reference an unknown target entity property: 
com.zack.music.domain.Composition.composition in com.zack.music.domain.Composer.compositions

以下是我的实体课程。我在这里做错了什么？

package com.zack.music.domain;

import javax.persistence.*;
import java.io.Serializable;
import java.sql.Date;
import java.util.*;

@Entity
public class Composer implements Serializable {

    @Id
    private String name;

    private Date birth;
    private Date death;

    @OneToMany(mappedBy="composition")
    private List<Composition> compositions;

    protected Composer() { }

    public Composer(String name, Date birth, Date death) {
        this.name = name;
        this.birth = birth;
        this.death = death;
    }

    public String getName() {
        return name;
    }

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

    public Date getBirth() {
        return birth;
    }

    public void setBirth(Date birth) {
        this.birth = birth;
    }

    public Date getDeath() {
        return death;
    }

    public void setDeath(Date death) {
        this.death = death;
    }

    public List<Composition> getCompositions() {
        return compositions;
    }

    public void setCompositions(List<Composition> compositions) {
        this.compositions = compositions;
    }
}

@Entity
public class Composition implements Serializable {

    @Id
    @Column(nullable = false)
    private String name;

    @ManyToOne  
    private Composer composer;

    protected Composition() { }

    public Composition(String name, Composer composer) {
        this.name = name;
        this.composer = composer;
    }

    public String getName() {
        return name;
    }

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

    public Composer getComposer() {
        return composer;
    }

    public void setComposer(Composer composer) {
        this.composer = composer;
    }
}

Answer 1

mappedBy告诉hibernate拥有该关系的相关实体的属性名称。没有名为＆＃39;组成的属性＆＃39;在相关实体上：Composition。您可能仅仅意味着mappedBy的值为"composer"。

Answer 2

我能够使用@ElementCollection来解决它。 Java Persistence/ElementCollection让我明白了。我还填写了所有表格和列中的“名称”属性，我认为这些属性有助于识别所有内容。以下是正在运行的更新实体：

package com.zack.music.domain;

import javax.persistence.*;
import java.io.Serializable;
import java.sql.Date;
import java.util.*;

@Entity(name="COMPOSER")
public class Composer implements Serializable {

    @Id
    @Column(name="NAME", nullable = false)
    private String name;

    @Column(name="BIRTH", nullable = false)
    private Date birth;

    @Column(name="DEATH", nullable = true)
    private Date death;

    @ElementCollection
    @CollectionTable(
            name="COMPOSITION",
            joinColumns=@JoinColumn(name="COMPOSER", referencedColumnName="NAME")
    )
    @Column(name="NAME")
    private List<String> compositions;

    protected Composer() { }

    public Composer(String name, Date birth, Date death) {
        this.name = name;
        this.birth = birth;
        this.death = death;
    }

    public String getName() {
        return name;
    }

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

    public Date getBirth() {
        return birth;
    }

    public void setBirth(Date birth) {
        this.birth = birth;
    }

    public Date getDeath() {
        return death;
    }

    public void setDeath(Date death) {
        this.death = death;
    }

    public List<String> getCompositions() {
        return compositions;
    }
}

@Entity(name="COMPOSITION")
public class Composition implements Serializable {

    @Id
    @Column(name="NAME", nullable = false)
    private String name;

    @Column(name="COMPOSER", nullable = false)
    private String composer;

    protected Composition() { }

    public Composition(String name, String composer) {
        this.name = name;
        this.composer = composer;
    }

    public String getName() {
        return name;
    }

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

    public String getComposer() {
        return composer;
    }

    public void setComposer(String composer) {
        this.composer = composer;
    }
}

休眠一对多注释混淆

2 个答案: