Java Spring数据JPA-保存重复的复合键时不'；我没有得到任何错误

我正在使用Postgres开发Spring Boot JPA复合键示例。在本例中，当我试图保存记录时，为什么看不到任何异常或约束冲突异常

SongId.java

@Data
@Builder
@AllArgsConstructor
@NoArgsConstructor
@Embeddable
public class SongId implements Serializable {
    private static final long serialVersionUID = 1L;

    private String name;
    private String album;
    private String artist;
}

public interface SongsRepository extends JpaRepository<Song, Long>{

}

Song.java

@Data
@Builder
@AllArgsConstructor
@NoArgsConstructor
@Entity
public class Song {
    @EmbeddedId 
    private SongId id;

    private int duration;
    private String genre;
    private LocalDateTime releaseDate;
    private int rating;
    private String downloadUrl;
}

SongsRepository.java

@Data
@Builder
@AllArgsConstructor
@NoArgsConstructor
@Embeddable
public class SongId implements Serializable {
    private static final long serialVersionUID = 1L;

    private String name;
    private String album;
    private String artist;
}

public interface SongsRepository extends JpaRepository<Song, Long>{

}

编辑-1: 我将SongsRepository.java更改为

public interface SongsRepository extends CrudRepository<Song, SongId>{}

日志：

2019-07-03 19:56:31.901  INFO 5420 --- [           main] .s.d.r.c.RepositoryConfigurationDelegate : Finished Spring Data repository scanning in 46ms. Found 1 repository interfaces.
2019-07-03 19:56:32.265  INFO 5420 --- [           main] com.zaxxer.hikari.HikariDataSource       : HikariPool-1 - Starting...
2019-07-03 19:56:32.378  INFO 5420 --- [           main] com.zaxxer.hikari.HikariDataSource       : HikariPool-1 - Start completed.
2019-07-03 19:56:32.415  INFO 5420 --- [           main] o.hibernate.jpa.internal.util.LogHelper  : HHH000204: Processing PersistenceUnitInfo [
    name: default
    ...]
2019-07-03 19:56:32.466  INFO 5420 --- [           main] org.hibernate.Version                    : HHH000412: Hibernate Core {5.3.10.Final}
2019-07-03 19:56:32.467  INFO 5420 --- [           main] org.hibernate.cfg.Environment            : HHH000206: hibernate.properties not found
2019-07-03 19:56:32.600  INFO 5420 --- [           main] o.hibernate.annotations.common.Version   : HCANN000001: Hibernate Commons Annotations {5.0.4.Final}
2019-07-03 19:56:32.747  INFO 5420 --- [           main] org.hibernate.dialect.Dialect            : HHH000400: Using dialect: org.hibernate.dialect.PostgreSQLDialect
2019-07-03 19:56:32.895  INFO 5420 --- [           main] o.h.e.j.e.i.LobCreatorBuilderImpl        : HHH000421: Disabling contextual LOB creation as hibernate.jdbc.lob.non_contextual_creation is true
2019-07-03 19:56:32.899  INFO 5420 --- [           main] org.hibernate.type.BasicTypeRegistry     : HHH000270: Type registration [java.util.UUID] overrides previous : org.hibernate.type.UUIDBinaryType@4ad3d266
Hibernate: 

    drop table if exists composite.song cascade
Hibernate: 

    create table composite.song (
       album varchar(255) not null,
        artist varchar(255) not null,
        name varchar(255) not null,
        download_url varchar(255),
        duration int4 not null,
        genre varchar(255),
        rating int4 not null,
        release_date timestamp,
        primary key (album, artist, name)
    )
2019-07-03 19:56:33.350  INFO 5420 --- [           main] o.h.t.schema.internal.SchemaCreatorImpl  : HHH000476: Executing import script 'org.hibernate.tool.schema.internal.exec.ScriptSourceInputNonExistentImpl@41ad373'
2019-07-03 19:56:33.352  INFO 5420 --- [           main] j.LocalContainerEntityManagerFactoryBean : Initialized JPA EntityManagerFactory for persistence unit 'default'
2019-07-03 19:56:33.404 DEBUG 5420 --- [           main] .c.JpaMetamodelMappingContextFactoryBean : Initializing JpaMetamodelMappingContext…
2019-07-03 19:56:33.410 DEBUG 5420 --- [           main] .c.JpaMetamodelMappingContextFactoryBean : Finished initializing JpaMetamodelMappingContext!
2019-07-03 19:56:33.557 DEBUG 5420 --- [           main] o.s.d.r.c.s.RepositoryFactorySupport     : Initializing repository instance for com.example.repository.SongsRepository…
2019-07-03 19:56:33.603 DEBUG 5420 --- [           main] o.s.d.j.r.query.JpaQueryFactory          : Looking up query for method findBySongId_AlbumAndSongId_ArtistAndSongId_Name
2019-07-03 19:56:33.604 DEBUG 5420 --- [           main] o.s.d.jpa.repository.query.NamedQuery    : Looking up named query Song.findBySongId_AlbumAndSongId_ArtistAndSongId_Name
2019-07-03 19:56:33.606 DEBUG 5420 --- [           main] o.s.d.jpa.repository.query.NamedQuery    : Did not find named query Song.findBySongId_AlbumAndSongId_ArtistAndSongId_Name
2019-07-03 19:56:33.646 DEBUG 5420 --- [           main] o.s.d.r.c.s.RepositoryFactorySupport     : Finished creation of repository instance for com.example.repository.SongsRepository.
2019-07-03 19:56:33.713  INFO 5420 --- [           main] com.example.CompositeApplication         : Started CompositeApplication in 2.59 seconds (JVM running for 3.333)
2019-07-03 19:56:33.722 DEBUG 5420 --- [           main] stomAnnotationTransactionAttributeSource : Adding transactional method 'saveAll' with attribute: PROPAGATION_REQUIRED,ISOLATION_DEFAULT
Hibernate: 
    select
        song0_.album as album1_0_0_,
        song0_.artist as artist2_0_0_,
        song0_.name as name3_0_0_,
        song0_.download_url as download4_0_0_,
        song0_.duration as duration5_0_0_,
        song0_.genre as genre6_0_0_,
        song0_.rating as rating7_0_0_,
        song0_.release_date as release_8_0_0_ 
    from
        composite.song song0_ 
    where
        song0_.album=? 
        and song0_.artist=? 
        and song0_.name=?
Hibernate: 
    insert 
    into
        composite.song
        (download_url, duration, genre, rating, release_date, album, artist, name) 
    values
        (?, ?, ?, ?, ?, ?, ?, ?)
Hibernate: 
    update
        composite.song 
    set
        download_url=?,
        duration=?,
        genre=?,
        rating=?,
        release_date=? 
    where
        album=? 
        and artist=? 
        and name=?
2019-07-03 19:56:33.773  INFO 5420 --- [       Thread-4] j.LocalContainerEntityManagerFactoryBean : Closing JPA EntityManagerFactory for persistence unit 'default'
2019-07-03 19:56:33.776  INFO 5420 --- [       Thread-4] com.zaxxer.hikari.HikariDataSource       : HikariPool-1 - Shutdown initiated...
2019-07-03 19:56:33.779  INFO 5420 --- [       Thread-4] com.zaxxer.hikari.HikariDataSource       : HikariPool-1 - Shutdown completed.

---

Spring数据Jpa存储库功能通过包含以下save（..）方法的SimpleParepository类实现：

更改：

public interface SongsRepository extends JpaRepository<Song, Long>

public interface SongsRepository扩展了JpaRepository

到

public interface SongsRepository扩展了JpaRepository

您根据存储库界面将密钥定义为

Long

。相反，它应该是正确的类型。接下来，由于生成的equals/hashcode，您将插入完全相同的实体，因此hibernate将检测到该实体为同一实体，并丢弃该实体。更改实体2的某些属性（而不是组成键的属性），这将使其失败。这是因为最终会进行

合并。默认的
isNew
检查检查id是否为
null
。在您的情况下，它不是，因此它将导致合并，从而更新第二个实体而不是新实体。@M.Deinum-您是对的。检查
isNew
后正在进行合并。你能指导我现在如何解决这个问题吗？你能为我分享stacktrace吗logs@MayurJain-添加了日志您可以使用自定义persist（）方法扩展spring数据jpa存储库，并通过EntityManager#persist（）实现它，EntityManager可以注入自定义方法的实现类中。请仅在initIdentifier（）内设置SongId对象。不要在生成歌曲时设置id。我不确定如何在initIdentifier（）中实际设置SongId对象。你能出示一些代码吗？那真的很有帮助。谢谢实际上不清楚在这里创建ID实例。

，如何从main方法设置它这不起作用。你能试一试吗？这是错误吗？如果这没有帮助，那么数据库中很可能存在问题。您确定您的

姓名

、

相册

和

艺术家

列是主键的一部分吗？对我来说，用作主键的组合似乎很奇怪。现在可以使用了，很抱歉我将

JpaRepository

更改为

crudepository

，这很好，但是，您的

song

表似乎是一个非常糟糕的数据库规范化示例。只需创建和<代码>艺术家< /代码>和<代码>专辑 ID和名称的表，并将它们作为外键键入你的代码>歌曲表中，歌曲可以由ID和ID标识。只是一个简单的例子，考虑你想找到一首歌，你需要知道这个名字，作者是谁以及包含它的专辑。但是我必须在歌曲模型类中放置

@PrePersist public void initIdentifier（SongId songId1）{if（SongId==null）{this.SongId=songId1；}}

，如果我不将数据保存。你知道为什么吗？

@Data
    @Builder
    @AllArgsConstructor
    @NoArgsConstructor
    @Entity
    public class Song {
        @EmbeddedId
        private SongId id;

        private int duration;
        private String genre;
        private LocalDateTime releaseDate;
        private int rating;
        private String downloadUrl;

    @PrePersist
    void initIdentifier() {
        SongId songId1 = SongId.builder().name("John").album("AlbumA").artist("ArtistA").build();
        if (id == null) {
            this.id = … songId1 // Create ID instance here.
        }
    }
    }

public interface SongsRepository extends JpaRepository<Song, Long>

public interface SongsRepository extends JpaRepository<Song, SongId>