Spring JPA @IdClass报错：实体中未找到对应属性问题

错误信息：

Caused by: org.hibernate.AnnotationException: Property of @IdClass not found in entity com.susanghan.spotrightspring.photo.domain.MemberSpotPhoto: SpotPhotoId
    at org.hibernate.cfg.AnnotationBinder.fillComponent(AnnotationBinder.java:2793) ~[hibernate-core-5.6.7.Final.jar:5.6.7.Final]
    at org.hibernate.cfg.AnnotationBinder.bindIdClass(AnnotationBinder.java:2919) ~[hibernate-core-5.6.7.Final.jar:5.6.7.Final]
    at org.hibernate.cfg.AnnotationBinder.mapAsIdClass(AnnotationBinder.java:1052) ~[hibernate-core-5.6.7.Final.jar:5.6.7.Final]
    at org.hibernate.cfg.AnnotationBinder.bindClass(AnnotationBinder.java:778) ~[hibernate-core-5.6.7.Final.jar:5.6.7.Final]
    at org.hibernate.boot.model.source.internal.annotations.AnnotationMetadataSourceProcessorImpl.processEntityHierarchies(AnnotationMetadataSourceProcessorImpl.java:225) ~[hibernate-core-5.6.7.Final.jar:5.6.7.Final]
    at org.hibernate.boot.model.process.spi.MetadataBuildingProcess$1.processEntityHierarchies(MetadataBuildingProcess.java:239) ~[hibernate-core-5.6.7.Final.jar:5.6.7.Final]
    at org.hibernate.boot.model.process.spi.MetadataBuildingProcess.complete(MetadataBuildingProcess.java:282) ~[hibernate-core-5.6.7.Final.jar:5.6.7.Final]
    at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.metadata(EntityManagerFactoryBuilderImpl.java:1460) ~[hibernate-core-5.6.7.Final.jar:5.6.7.Final]
    at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.build(EntityManagerFactoryBuilderImpl.java:1494) ~[hibernate-core-5.6.7.Final.jar:5.6.7.Final]

涉及类代码 #

MemberSpotPhotoPK 类 #

@Getter
@NoArgsConstructor
@AllArgsConstructor
public class MemberSpotPhotoPK implements Serializable {

    private static final Long serialVersionUID = 1L;

    private Long memberSpotId;
    private Long SpotPhotoId;
}

MemberSpotPhoto 实体类 #

@Getter
@Entity
@NoArgsConstructor(access = AccessLevel.PROTECTED)
@IdClass(MemberSpotPhotoPK.class)
public class MemberSpotPhoto extends BaseTimeEntity {

    @Id
    @Column(insertable = false, updatable = false)
    private Long memberSpotId;

    @Id
    @Column(insertable = false, updatable = false)
    private Long spotPhotoId;

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "member_spot_id", referencedColumnName = "member_spot_id", insertable = false, updatable = false)
    private MemberSpot memberSpot;

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "spot_photo_id", referencedColumnName = "spot_photo_id", insertable = false, updatable = false)
    private SpotPhoto spotPhoto;

    private Byte order;

    @Builder
    public MemberSpotPhoto(Long memberSpotId, Long spotPhotoId, Byte order) {
        this.memberSpotId = memberSpotId;
        this.spotPhotoId = spotPhotoId;
        this.order = order;
    }
}

MemberSpot 实体类 #

@Getter
@Entity
@NoArgsConstructor(access = AccessLevel.PROTECTED)
public class MemberSpot extends BaseTimeEntity {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "member_spot_id")
    private Long id;
    
    ....
}

SpotPhoto 实体类 #

@Getter
@Entity
@NoArgsConstructor(access = AccessLevel.PROTECTED)
public class SpotPhoto extends BaseTimeEntity {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "spot_photo_id")
    private Long id;

    ....
}

问题原因及修复 #

问题根源是属性名称大小写不匹配：

• MemberSpotPhotoPK 类中的属性名为 SpotPhotoId（首字母大写）
• MemberSpotPhoto 实体中的对应属性名为 spotPhotoId（首字母小写）

Hibernate 使用 @IdClass 时，要求主键类的属性名与实体类中的主键属性名完全一致（包括大小写），否则无法完成属性映射，抛出上述异常。

修复方法：修改 MemberSpotPhotoPK 类中的属性名，使其与实体类保持一致，将 SpotPhotoId 改为 spotPhotoId：

@Getter
@NoArgsConstructor
@AllArgsConstructor
public class MemberSpotPhotoPK implements Serializable {

    private static final Long serialVersionUID = 1L;

    private Long memberSpotId;
    // 修正属性名大小写
    private Long spotPhotoId;
}

内容的提问来源于stack exchange，提问作者gs97ahn