NativeQuery Spring Data返回对象

Question

我需要在Spring Data中实现这样的查询: -

Select User.name, sum(Activity.minutes) 
From User, Activity, ActivityStatus
Where User.id = ActivityStatus.userId
And Activity.id = ActivityStatus.activityId
AND ActivityStatus = "COMPLETED"
GROUP BY user.name;

所以我需要参加3个表,所以我必须使用@Query与nativeQuery = true(纠正我,如果我错了这里)

所以我的Repository方法看起来像这样: -

@Query(value = "Select User.name, sum(Activity.minutes) as total_minutes
    From User, Activity, ActivityStatus
    Where User.id = ActivityStatus.userId
    And Activity.id = ActivityStatus.activityId
    AND ActivityStatus = "COMPLETED"
    AND User.Type = ?1
    GROUP BY user.name;",
    nativeQuery = true
    )
List<MyObj> getTotalActivityMinutesByUserType(String userType);

MyObj class看起来像这样: -

public class MyObj {
    String name;
    long total_minutes;

// getter and setter methods

    public MyObj(String name, long total_minutes) {
        this.name = name;
        this.total_minutes = total_minutes;
    }
}

我的测试方法: -

@Test
public void TotalActivityTest() throws Exception {
    List<MyObj> objA = myRepository.getTotalActivityMinutesByUser("TEST");

}

我得到以下例外: -

org.springframework.core.convert.ConversionFailedException:无法从类型[java.lang.Object []]转换为类型为"{TEST,5.0}"的类型[com.mycomp.MyObj]; 嵌套异常是org.springframework.core.convert.ConverterNotFoundException:找不到能够从类型[java.lang.String]转换为类型[com.mycomp.dto.MyObj]的转换器

我需要一种方法来返回结果MyObj.(或者至少是将它投射到MyObj的方法)这可能吗？

编辑:

从@ Cepr0的回答构建My Entity类看起来像这样: -

@Entity
public class ActivityStatus extends Base {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @ManyToOne(cascade = {CascadeType.PERSIST, CascadeType.MERGE, CascadeType.REFRESH, CascadeType.DETACH})
    private Activity activity;

    @ManyToOne(cascade = {CascadeType.PERSIST, CascadeType.MERGE, CascadeType.REFRESH, CascadeType.DETACH})
    private User user;

}

我不确定JPQL中的JOIN查询应该如何...

Answer 1

只需使用Projection和JPQL查询:

public interface NameAndDuration {
    String getName();
    Long getDuaration();
}

@Query("select u.name as name, sum(a.minutes) as duration from User u join u.activityStatus st join st.activity a where st.status = "COMPLETED" and u.type = ?1 group by u.name")
List<NameAndDuration> getNameAndDurationByUserType(String userType);

List<NameAndDuration> list = getNameAndDurationByUserType("TEST");
String userName = list.get(0).getName();

此查询可能不是您需要的,因为我不知道您的实体类的结构.但是如果你展示它们我将更正查询......