父接口上的Spring Data JPA JPQL查询 [英] Spring Data JPA JPQL queries on parent interface

问题描述

说我有一个像这样的@MappedSuperClass:

@MappedSuperclass
public abstract class Rating
{
    @Id
    private Long id;

    @Column(name="USER_ID")
    private Long userId;

    private int rating;
    ...

具有这样的具体子实体

@Entity
@Table(name="ACTIVITY_RATING")
public class ActivityRating extends Rating
{
    private Long activitySpecificData;
    ...

然后有一个像这样的Spring Data JPA存储库:

Then there is a Spring Data JPA repository like this:

@NoRepositoryBean
public interface RatingRepository<R extends Rating> extends JpaRepository<R, ID>
{
    public List<R> findByUserId(Long userId);
    ...

和这个:

public interface ActivityRatingRepository extends RatingRepository<ActivityRating>
{

}

这一切都很好，我可以在扩展RatingRepository的任何特定评级存储库中调用findByUserId().我现在想在所有子接口都可以继承的RatingRepository中编写一些JPQL.我只是不知道在查询中FROM之后要放什么(或什至有可能).例如:

This all works great and I can call findByUserId() on any of specific rating repositories that extend RatingRepository. I am now wanting to write some JPQL in the RatingRepository that all the child interfaces can inherit. I just don't know what (or if it's even possible) to put after the FROM in the query. For example:

@Query("SELECT NEW com.foo.RatingCountVo(e.rating, COUNT(e.rating)) FROM ??????? e GROUP BY e.rating")
public List<RatingCountVo> getRatingCounts();

我可以将此方法添加到扩展RatingRepository的每个单独的存储库中，但是除了特定的实体名称之外，其他所有内容都将完全相同.如果要更改查询，则必须转到所有子存储库并分别进行更新.我真的希望查询生活在父类中，而不是重复的.有什么办法可以做到这一点?

I can add this method to each of the individual repositories that extend RatingRepository but everything would be exactly the same except for the specific entity name. If I want to change the query, I'd then have to go to all the child repositories and update them individually. I really want the query to live in the parent class and not be duplicated. Is there any way to accomplish this?

我目前正在使用spring-data-jpa 1.7.2和eclipselink 2.5.2.我不一定非要在必要时切换到较新版本.

I'm currently using spring-data-jpa 1.7.2 and eclipselink 2.5.2. I'm not necessarily opposed to switching to newer versions if necessary.

推荐答案

如果将查询分为三个部分，它将开始工作吗:查询的开始，实体和结束?然后，如果可以的话，在每个接口中定义

Will it work if you will split query into 3 parts: start, entity and end of query? Than, if it'll work, in each interface you define constant like

String ENTITY = "ActivityRating";

然后您可以像使用它

@Query(RatingRepository.QUERY_START + ENTITY + RatingRepository.QUERY_END)
List<RatingCountVo> getRatingCounts();

顺便说一句，不需要在界面中定义public修饰符.

BTW, there is no need to define public modifier in interface.

更新:此处描述的另一种方式:

@Query("SELECT NEW com.foo.RatingCountVo(e.rating, COUNT(e.rating)) FROM #{#entityName} e GROUP BY e.rating

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