无法使用@IdClass转换实体中的请求元素 [英] Failed to convert request element in entity with @IdClass

问题描述

  @Entity 
 @IdClass（MemberAttributePk.class）
 public class MemberAttribute {
 @Id 
 @ManyToOne @JoinColumn（name =member_id）
保护成员成员; 
 
 @Id 
受保护的字符串名称; 
 
私有字符串值; 
 
 public MemberAttribute（）{} 
 
 // get&设置
} 
  

和id类：

  public class MemberAttributePk implements Serializable {
 protected member member; 
保护字符串名称; 
 
 public MemberAttributePk（）{} 
 
 // get& set 
} 
  

我为定义了一个简单的Spring Data存储库， MemberAttribute ：

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

现在，我要做的就是将成员属性保存到数据库：

  public void saveAttribute（Member member，String name，String value）{
 MemberAttribute attr = new MemberAttribute（member ，名称，价值）; 
 attributeRepo.save（attr）; 
} 
  

然而，我最终发现这个服务器异常：

  2016-08-28 00：24：20.673 WARN 5656 --- [nio-8080-exec-8] .wsmsDefaultHandlerExceptionResolver：
无法转换请求元素：org.springframework.beans.ConversionNotSupportedException：
无法将[java.lang.Long]类型的属性值转换为属性'member'所需的类型[com.example.Member];嵌套异常是java.lang.IllegalStateException：
无法将属性'member'的类型[java.lang.Long]的值转换为所需类型[com.example.Member]：
没有匹配的编辑器或转换战略发现
  

任何想法我做错了什么？
Thanks！

解决方案

简单地说你的代码不符合JPA。问题的原因是你使用 Member 作为PK的一部分。
PK只能由以下Java类型的字段组成

1. 基元：布尔型，字节型，char型，int型，long型，short型
   
2. java.lang 字符，整数，长，短，字符串，枚举，StringBuffer


3. java.math ：BigInteger java.sql：Date，Time，Timestamp


4. java.util ：日期，货币，区域设置，TimeZone，UUID URL


5. javax.jdo.spi ：PersistenceCapable

---

这应该有效：

  @Embeddable 
 public class MemberAttributePk实现Serializable {
 @Column（name =member_id）
 protected long memberId; 
 @Column（name =name）
保护字符串名称; 
 
 public MemberAttributePk（）{} 
 
 // get& set 
} 
 
 @Entity 
 public class MemberAttribute {
 
 @EmbeddedId 
 protected MemberAttributePk memberAttributePk; 
 
 @ManyToOne 
 @JoinColumn（name =member_id）
保护会员; 
 
私有字符串值; 
 
 public MemberAttribute（）{} 
 
 // get&设置
} 
  

或者与 @ClassId
$ p $ public class MemberAttributePk implements Serializable {
protected long memberId;
保护字符串名称;

public MemberAttributePk（）{}

// get&设置
}

@Entity
@IdClass（MemberAttributePk.class）
public class MemberAttribute {
@Id
@Column（name = member_id）
保护长会员Id;

@Id
@Column（name =name）
保护字符串名称;

@ManyToOne
@JoinColumn（name =member_id）
保护会员;

私有字符串值;

public MemberAttribute（）{}

// get&设置
}





I have the following setup:

@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
}

And the id class:

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

    public MemberAttributePk() {}

    // get & set
}

I have defined a simple Spring Data repository for MemberAttribute:

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

Now, all I want to do is persist a member attribute to the database:

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

However, I end up with this server exception:

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

Any idea what am I doing wrong? Thanks!

解决方案

Simply your code is not JPA compliant. The cause of problem is that you use Member as a part of your PK. The PK can only be made up of fields of the following Java types

1. Primitives : boolean , byte , char , int , long , short
2. java.lang : Boolean , Byte , Character , Integer , Long , Short , String , Enum , StringBuffer
3. java.math : BigInteger java.sql : Date , Time , Timestamp
4. java.util : Date , Currency, Locale, TimeZone, UUID
5. java.net : URI, URL
6. javax.jdo.spi : PersistenceCapable

---

This should work:

@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
}

Or the same with @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
}

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