Problem with querying entities with a set of entities in Spring Boot @Query

Question

I want to have a Spring Boot @Query in JpaRepository which returns me entities with a set of other entities. I know that I can use findAll() method, and then take only those rows that I'm interested in, but I think that this is much slower. The problem is that my entity Booster contains a Set of other entities Boost, and when i try to query it, I get an error. So, this is my 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 findBoostersForOverview(String game);

These are my entity classes:

@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 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 games;
    private String game;
    private String additionalInformation;
    private String server;

This is what console shows:

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

And this is error i get:
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

I know that I can query without Set of Boost, and then in another query get specific Boosts, but in my app there will be a lot of SQL and my code will turn to spaghetti. Is there a simple way to solve my problem?

user_7875623 · Answer

Can you add the following to your repository without any @Query annotation and see?

    List findByGamesLikeAndBoostsFinishedIsTrue(String game);

user_1862590 · Answer

The problem here, you are using GROUP BY. When you are using Group By you have use aggregate functions (COUNT, MAX, MIN, SUM, AVG) to group the result-set by one or more columns in the select column. Aggregate functions are mandatory when using GROUP BY function.

In your case, I hope Group By is not required. Modify your code like below.

@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 findBoostersForOverview(String game);

Problem with querying entities with a set of entities in Spring Boot @Query

2 Answers