在 Spring Boot @Query 中使用一组实体查询实体的问题

Question

我想在 JpaRepository 中有一个 Spring Boot @Query，它返回带有一组其他实体的实体。我知道我可以使用findAll() 方法，然后只取那些我感兴趣的行，但我认为这要慢得多。问题是我的实体Booster 包含其他实体Set 的Boost，当我尝试查询它时，出现错误。所以，这是我的Query：

    @Query( "select new app.model.Booster(" +
            "   B.id, " +
            "   B.active, " +
            "   B.games, " +
            "   B.ownerAccount, " +
            "   B.boosts, " +
            "   B.boosterNickname, " +
            "   B.additionalInformation) " +
            "from " +
            "   Booster B " +
            "   left join Boost Bo on B.id = Bo.boostingAccount.id " +
            "where " +
            "   B.games like %?1% " +
            "   and Bo.finished = true " +
            "group by " +
            "   B.id")
    List<Booster> findBoostersForOverview(String game);

这些是我的实体类：

@Data
@Entity(name = "Booster")
public class Booster {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long id;
    private boolean active;
    private String games;
    @OneToOne(mappedBy = "boosterAccount", cascade = CascadeType.ALL, fetch = FetchType.EAGER)
    private Account ownerAccount;
    @OneToMany(mappedBy = "boostingAccount", cascade = CascadeType.ALL, fetch = FetchType.EAGER)
    private Set<Boost> boosts;
    private String boosterNickname;
    private String additionalInformation;

@Data
@Entity(name = "Boost")
public class Boost {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name="id",nullable=false,unique=true)
    private long id;
    private Date dateCreated;
    private Date dateFinished;
    private Date dateLastModification;
    private boolean finished;
    private boolean paused;
    @ManyToOne(fetch = FetchType.EAGER)
    @JoinColumn(name = "boosted_account_id", referencedColumnName = "id")
    private Account boostedAccount;
    @ManyToOne(fetch = FetchType.EAGER)
    @JoinColumn(name = "boosting_account_id", referencedColumnName = "id")
    private Booster boostingAccount;
    @OneToMany(mappedBy = "boost", cascade = CascadeType.ALL, fetch = FetchType.EAGER)
    private Set<Game> games;
    private String game;
    private String additionalInformation;
    private String server;

这是控制台显示的内容：

Hibernate: 
    select
        booster0_.id as col_0_0_,
        booster0_.active as col_1_0_,
        booster0_.games as col_2_0_,
        booster0_.id as col_3_0_,
        . as col_4_0_,
        booster0_.booster_nickname as col_5_0_,
        booster0_.additional_information as col_6_0_ 
    from
        booster booster0_ 
    //HERE IS SOME MORE LOGS THAT ARE UNNECESSARY HERE

这是我得到的错误：
java.sql.SQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '. as col_4_0_, booster0_.booster_nickname as col_5_0_, booster0_.additional_info' at line 1

我知道我可以在没有Set 或Boost 的情况下进行查询，然后在另一个查询中获取特定的Boosts，但是在我的应用程序中会有很多SQL，我的代码会变成意大利面条。有没有简单的方法可以解决我的问题？

Answer 1

您能否将以下内容添加到您的存储库中没有任何@Query 注释并查看？

    List<Booster> findByGamesLikeAndBoostsFinishedIsTrue(String game);

Answer 2

这里的问题，你正在使用GROUP BY。当您使用Group By 时，您可以使用聚合函数(COUNT, MAX, MIN, SUM, AVG) 将结果集按选择列中的一列或多列分组。使用 GROUP BY 函数时，聚合函数是强制。

在您的情况下，我希望 Group By 不是必需的。修改您的代码，如下所示。

@Query( "select new app.model.Booster(" +
        "   B.id, " +
        "   B.active, " +
        "   B.games, " +
        "   B.ownerAccount, " +
        "   B.boosts, " +
        "   B.boosterNickname, " +
        "   B.additionalInformation) " +
        "from " +
        "   Booster B " +
        "   left join Boost Bo on B.id = Bo.boostingAccount.id " +
        "where " +
        "   B.games like %?1% " +
        "   and Bo.finished = true")
List<Booster> findBoostersForOverview(String game);