java - JPA Hibernate删除实体的子对象，与双PK触发SQL更新而不是删除连接？

Question

我有以下表结构:

• 每个 chat_bot 可以有多个版本。
• 每个版本都可以部署到环境中。
• 版本具有双主键，其中之一是从 chat_bot 表引用的。
• 环境表只有主键。其中两个是从版本表中引用的。

我有以下类结构:

@Entity
@AllArgsConstructor
@Table(name = "chat_bot")
@NoArgsConstructor
public class Bot {

    @Id
    private String id;

    @LazyCollection(LazyCollectionOption.FALSE)
    @OneToMany(mappedBy = "botId", cascade = CascadeType.ALL, orphanRemoval = true)
    private Set<BotVersion> versions = new LinkedHashSet<>();
}

@AllArgsConstructor
@NoArgsConstructor
@EqualsAndHashCode
public class BotVersionPK implements Serializable {
    private String botId;
    private int version;
}


@Entity
@AllArgsConstructor
@Table(name = "chat_bot_version")
@NoArgsConstructor
@IdClass(BotVersionPK.class)
public class BotVersion {

    @Id
    private String botId;
    @Id
    private int version;

    @Type(type = "text")
    private String json;

    @OneToMany(fetch = FetchType.LAZY, orphanRemoval = true)
    @JoinColumns({
            @JoinColumn(name = "botId", referencedColumnName = "botId"),
            @JoinColumn(name = "version", referencedColumnName = "version")
    })
    private Set<BotEnvironments> environments = new LinkedHashSet<>();
}

@AllArgsConstructor
@NoArgsConstructor
@EqualsAndHashCode
public class BotEnvironmentsPK implements Serializable {
    private String botId;
    private int version;
    private String environmentCode;
}

@Entity
@NoArgsConstructor
@AllArgsConstructor
@Table(name = "chat_bot_environments")
@IdClass(BotEnvironmentsPK.class)
public class BotEnvironments {
    @Id
    private String botId;
    @Id
    private int version;
    @Id
    private String environmentCode;
}

我使用 JpaRepository< Bot, String > 来加载和保存信息。

问题:如果我从“环境”集中删除一个项目并将其保留，Hibernate 不会触发 DELETE 操作，而是触发 UPDATE 操作:

update chat_bot_environments set bot_id=null, version=null where bot_id=? and version=?

我收到以下错误，该错误是有效的:

Column 'bot_id' cannot be null

为什么 Hibernate JPA 触发器更新而不是删除？如何删除通过非空 PK 连接的子元素？

Answer 1

您的映射存在一些错误。

1. 连接列始终位于子端:

   @OneToMany(fetch = FetchType.LAZY, orphanRemoval = true)
   @JoinColumns({
           @JoinColumn(name = "botId", referencedColumnName = "botId"),
           @JoinColumn(name = "version", referencedColumnName = "version")
   })
   private Set<BotEnvironments> environments = new LinkedHashSet<>();
   

此映射应移至子级 (BotEnvironments)。

mappedBy 应指向与实体相同类型的字段。您已定义 mappedBy = "botId"，但 botId 的类型为 String(它是外键)。这不会映射实体之间的关系。

不要害怕双向关系。它们不会造成性能开销 - 实际上它们通常可以优化持久性性能。

我还纠正了其他一些小问题。为了简洁起见，我省略了 Lombok 注释和获取类型。这是正确的映射(生成的结果数据库架构是相同的):

机器人:

@Entity
@Table(name = "chat_bot")
public class Bot {

    @Id
    private String id;

    @OneToMany(mappedBy = "bot", cascade = CascadeType.ALL, orphanRemoval = true)
    private Set<BotVersion> versions = new LinkedHashSet<>();

}

机器人版本:

@Entity
@Table(name = "chat_bot_version")
@IdClass(BotVersionPK.class)
public class BotVersion {

    @Id
    private String botId;
    @Id
    private int version;

    @ManyToOne
    @JoinColumn(name = "botId", insertable=false, updatable=false)
    private Bot bot;

    @Type(type = "text")
    private String json;

    @OneToMany(cascade = CascadeType.ALL, orphanRemoval = true, mappedBy = "botVersion")
    private Set<BotEnvironments> environments = new LinkedHashSet<>();

}

机器人环境:

@Entity
@Table(name = "chat_bot_environments")
@IdClass(BotEnvironmentsPK.class)
public class BotEnvironments {
    @Id
    private String botId;
    @Id
    private int version;
    @Id
    private String environmentCode;

    @ManyToOne
    @JoinColumns({
            @JoinColumn(name = "botId", referencedColumnName = "botId", insertable=false, updatable=false),
            @JoinColumn(name = "version", referencedColumnName = "version", insertable=false, updatable=false)
    })
    private BotVersion botVersion;

}

Id 类未更改。

这是一个简单的测试，用于检查其是否有效:

@Test
public void test() {
    // given
    BotEnvironments botEnvironments = new BotEnvironments("bid", 1, "env");
    BotEnvironments botEnvironments1 = new BotEnvironments("bid", 1, "env1");
    BotVersion botVersion = new BotVersion("bid", 1, "json", Set.of(botEnvironments, botEnvironments1));
    Bot bot = new Bot("bid", Set.of(botVersion));
    botRepository.save(bot);

    // when
    Bot savedBot = botRepository.findAll().get(0);
    savedBot.getVersions().iterator().next().getEnvironments().remove(savedBot.getVersions().iterator().next().getEnvironments().iterator().next());
    botRepository.save(savedBot);

    // then
    assertEquals(1, botEnvironmentsRepository.findAll().size());
}