无法从PostgreSQL获取JPA数据：参数类型不匹配错误求助

问题描述 #

存在一对OneToMany关联的实体GroupChat和MessengerUser，数据已成功存入PostgreSQL数据库，但调用接口获取群聊数据时抛出参数类型不匹配错误，提示Long类型参数与GroupChat类型不匹配。虽然Hibernate已成功查询到群聊数据，但无法正常返回对象。

错误日志 #

Hibernate: select g1_0.id,g1_0.analysed_date,g1_0.creation_date,g1_0.expiration_date,g1_0.group_chat_name,g1_0.total_current_participants,g1_0.total_messages,g1_0.total_participants,g1_0.total_sent_audio_files,g1_0.total_sent_gifs,g1_0.total_sent_photos,g1_0.total_sent_reactions,g1_0.total_sent_videos,g1_0.unique_id from group_chat g1_0 where g1_0.unique_id=?
2022-12-04T14:06:41.751Z ERROR 16704 --- [nio-8080-exec-1] o.a.c.c.C.[.[.[/].[dispatcherServlet]    : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed: org.springframework.dao.InvalidDataAccessApiUsageException: Argument [3] of type [java.lang.Long] did not match parameter type [com.example.demo.models.GroupChat (n/a)]] with root cause

java.lang.IllegalArgumentException: Argument [3] of type [java.lang.Long] did not match parameter type [com.example.demo.models.GroupChat (n/a)]

实体模型代码 #

GroupChat实体 #

@Entity
@Getter @Setter @NoArgsConstructor
@Table(name = "GroupChat")
public class GroupChat extends RepresentationModel<GroupChat> {

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

    @Column(name = "uniqueId", nullable = false, unique=true)
    private UUID uniqueId;

    @Column(name = "expirationDate")
    private Date expirationDate;

    @Column(name = "analysedDate")
    private Date analysedDate;

    @Column(name = "creationDate")
    private Date creationDate;

    @Column(name = "totalParticipants", nullable = false)
    private int totalParticipants;

    @Column(name = "totalCurrentParticipants", nullable = false)
    private int totalCurrentParticipants;

    @Column(name = "totalMessages", nullable = false)
    private int totalMessages;

    @Column(name = "totalSentVideos", nullable = false)
    private int totalSentVideos;

    @Column(name = "totalSentPhotos", nullable = false)
    private int totalSentPhotos;

    @Column(name = "totalSentGifs", nullable = false)
    private int totalSentGifs;

    @Column(name = "totalSentAudioFiles", nullable = false)
    private int totalSentAudioFiles;

    @Column(name = "totalSentReactions", nullable = false)
    private int totalSentReactions;

    @Column(name = "groupChatName")
    private String groupChatName;

    @Column(name = "participants")
    @OneToMany(mappedBy="groupChatId", fetch = FetchType.LAZY,
            cascade = CascadeType.ALL)
    private List<MessengerUser> participants;

}

MessengerUser实体 #

@Entity
@Getter
@Setter
@NoArgsConstructor
@Table(name = "MessengerUser")
public class MessengerUser extends RepresentationModel<MessengerUser> {

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

    @Column(name = "name", nullable = false)
    private String name;

    @Column(name = "profilePic")
    private int profilePic;

    @Column(name = "numberOfMessagesSent")
    private int numberOfMessagesSent;

    @Column(name = "numberOfPhotosSent")
    private int numberOfPhotosSent;

    @Column(name = "numberOfVideosSent")
    private int numberOfVideosSent;

    @Column(name = "numberOfGifsSent")
    private int numberOfGifsSent;

    @Column(name = "numberOfAudioFilesSent")
    private int numberOfAudioFilesSent;

    @Column(name = "numberOfReceivedReactions")
    private int numberOfReceivedReactions;

    @Column(name = "numberOfSentReactions")
    private int numberOfSentReactions;

    @Column(name = "userReactionsReceived", columnDefinition="TEXT")
    @Lob
    private String userReactionsReceived;

    @Column(name = "userReactionsSent", columnDefinition="TEXT")
    @Lob
    private String userReactionsSent;

    @Column(name = "addedToChat", columnDefinition="TEXT")
    @Lob
    private String addedToChat;

    @Column(name = "removedFromChat", columnDefinition="TEXT")
    @Lob
    private String removedFromChat;

    @Column(name = "firstRecordOfActivity")
    private Date firstRecordOfActivity;

    @Column(name = "lastRecordOfActivity")
    private Date lastRecordOfActivity;

    @Column(name = "userActiveStatus")
    private Boolean userActiveStatus;

    @Column(name = "firstMessage")
    private String firstMessage;

    @Column(name = "firstMessageDate")
    private Date firstMessageDate;

    @Column(name = "message")
    private int message;

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name="group_chat_id", nullable=false)
    private GroupChat groupChatId;

}

控制器与仓库代码 #

GroupChatController相关方法 #

@GetMapping("/{uniqueId}/chat")
public GroupChat getGroupChatByUniqueId(@PathVariable(value = "uniqueId") UUID uniqueId) {
    GroupChat g = groupChatRepository.findByUniqueId(uniqueId);
    Link selfLink = linkTo(methodOn(GroupChatController.class)
            .getGroupChatByUniqueId(uniqueId)).withSelfRel();
    g.add(selfLink);
    if (messengerUserRepository.findByGroupChatId(g.getId()).size() > 0) {
        Link ordersLink = linkTo(methodOn(MessengerUserController.class)
                .getMessengerUsersByGroupChatId(g.getId(),uniqueId))
                .withRel("allMessengerUsers");
        g.add(ordersLink);
    }
    return g;
}

GroupChatRepository #

public interface GroupChatRepository extends JpaRepository<GroupChat, Long> {

    GroupChat findByUniqueId(UUID uniqueId);
}

错误原因及解决方案 #

错误根源 #

错误核心出现在**messengerUserRepository.findByGroupChatId(g.getId())**这一行：

• 在MessengerUser实体中，关联字段定义为private GroupChat groupChatId;，对应的JPA查询方法findByGroupChatId预期接收的参数类型是GroupChat对象，而非Long类型的ID值。传入g.getId()（Long类型）就会触发类型不匹配错误。

修复步骤 #

1. 调整MessengerUserRepository查询方法：
   若要通过GroupChat的ID查询MessengerUser，需定义正确的查询方法：

   // 方法1：通过关联对象的ID查询
   List<MessengerUser> findByGroupChatId_Id(Long groupChatId);
   // 方法2：判断是否存在数据（性能更优）
   boolean existsByGroupChatId_Id(Long groupChatId);
   

2. 修改控制器调用逻辑：
   将原代码中的messengerUserRepository.findByGroupChatId(g.getId()).size() > 0替换为：

   if (messengerUserRepository.existsByGroupChatId_Id(g.getId())) {
       // 原逻辑不变
   }
   

3. 额外规范建议：

   • 实体关联字段命名需清晰，建议将groupChatId改为groupChat，避免字段名与ID语义混淆：

     @ManyToOne(fetch = FetchType.LAZY)
     @JoinColumn(name="group_chat_id", nullable=false)
     private GroupChat groupChat; // 更名后更符合语义
     

     对应的Repository方法改为findByGroupChat_Id(Long groupChatId)或existsByGroupChat_Id(Long groupChatId)。

内容的提问来源于stack exchange，提问作者MSmith