Java 无法转换具有@IdClass的实体中的请求元素

我有以下设置：

@Entity
@IdClass(MemberAttributePk.class)
public class MemberAttribute {
    @Id
    @ManyToOne @JoinColumn(name="member_id")
    protected Member member;

    @Id
    protected String name;

    private String value;

    public MemberAttribute() {}

    // get & set
}

和id类：

public class MemberAttributePk implements Serializable {
    protected Member member;
    protected String name;

    public MemberAttributePk() {}

    // get & set
}

我已经为

MemberAttribute

定义了一个简单的Spring数据存储库：

@Repository
public interface MemberAttributeRepo extends JpaRepository<MemberAttribute, MemberAttributePk> {
}

但是，我最终遇到了以下服务器异常：

2016-08-28 00:24:20.673  WARN 5656 --- [nio-8080-exec-8] .w.s.m.s.DefaultHandlerExceptionResolver : 
Failed to convert request element: org.springframework.beans.ConversionNotSupportedException: 
Failed to convert property value of type [java.lang.Long] to required type [com.example.Member] for property 'member'; nested exception is java.lang.IllegalStateException: 
Cannot convert value of type [java.lang.Long] to required type [com.example.Member] for property 'member': 
no matching editors or conversion strategy found

知道我做错了什么吗？

---

谢谢

只是您的代码不符合JPA。问题的原因是您使用

成员

作为PK的一部分。 主键只能由以下Java类型的字段组成

原语：布尔、字节、字符、整数、长、短

java.lang：布尔值、字节、字符、整数、长、短、字符串、枚举、字符串缓冲区

java.math：biginger java.sql:Date、Time、Timestamp

java.util：日期、货币、地区、时区、UUID

java.net：URI，URL

javax.jdo.spi：支持持久性

---

这应该起作用：

@Embeddable
public class MemberAttributePk implements Serializable {
    @Column(name = "member_id")
    protected Long memberId;
    @Column(name = "name")
    protected String name;

    public MemberAttributePk() {}

    // get & set
}

@Entity
public class MemberAttribute {

    @EmbeddedId
    protected MemberAttributePk memberAttributePk;

    @ManyToOne 
    @JoinColumn(name="member_id")
    protected Member member;

    private String value;

    public MemberAttribute() {}

    // get & set
}

或与

@ClassId

public class MemberAttributePk implements Serializable {
    protected Long memberId;
    protected String name;

    public MemberAttributePk() {}

    // get & set
}

@Entity
@IdClass(MemberAttributePk.class)
public class MemberAttribute {
    @Id
    @Column(name = "member_id")
    protected Long memberId;

    @Id
    @Column(name = "name")
    protected String name;

    @ManyToOne 
    @JoinColumn(name="member_id")
    protected Member member;

    private String value;

    public MemberAttribute() {}

    // get & set
}

---

您可以尝试使用MemberRepository保存它，因为我相信您的成员类和MemberAttribute类具有一对多关系引用，下面是示例

成员类

@Entity
public class Member {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    public long id;

    @OneToMany(mappedBy = "Member", cascade = CascadeType.ALL)
     private Set<MemberAttribute> mMemberAttributes = new HashSet<>();

     public void setMemberAttributes(Set<MemberAttribute> mMemberAttributes){
        this.mMemberAttributes = mMemberAttributes;
     }

     public Set<MemberAttribute> getMemberAttributes(){
         return mMemberAttributes;
     }

     // other code
}

---

谢谢就这样。稍微提到一下，

成员

应该映射为：

@ManyToOne@JoinColumn（name=“Member\u id”，insertable=false，updateable=false）

@Entity
public class Member {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    public long id;

    @OneToMany(mappedBy = "Member", cascade = CascadeType.ALL)
     private Set<MemberAttribute> mMemberAttributes = new HashSet<>();

     public void setMemberAttributes(Set<MemberAttribute> mMemberAttributes){
        this.mMemberAttributes = mMemberAttributes;
     }

     public Set<MemberAttribute> getMemberAttributes(){
         return mMemberAttributes;
     }

     // other code
}

public interface MemberRepository extends JpaRepository<Member, Long> {

}

public void saveAttribute(Member member, String name, String value) {
    MemberAttribute attr = new MemberAttribute(member, name, value);
    member.getMemberAttributes().add(attr);
    memberRepository.save(member);
}