Spring Data JPA中的动态查询 [英] Dynamic Queries in Spring Data JPA

问题描述

我正在寻找一种解决方案来动态构建使用Spring Data JPA的查询。我有一个GameController，它有一个RESTful服务端点/游戏，它需要4个可选参数：流派，平台，年份，标题。这些API可能不会被传递，全都是4，以及它们之间的每个组合。如果任何参数未通过，则默认为空。我需要一个存储库中的方法来构建适当的查询，理想情况下仍然允许Spring Data JPA Paging，尽管我不确定这是否可行。

I发现这篇文章，但这似乎并不是我所需要的，除非我误解。 http://spring.io/ blog / 2011/04/26 / advanced-spring-data-jpa-specifications-and-querydsl /

我知道JPA有Query Criteria API，但真的不知道如何实现这一点。

我意识到我可以为每个可能的场景创建一个方法，但这似乎是非常糟糕的做法和大量不必要的代码。

GameRepository：

  package net.jkratz.igdb.repository; 
 
导入net.jkratz.igdb.model.Game; 
 import org.springframework.data.domain.Page; 
 import org.springframework.data.domain.Pageable; 
 import org.springframework.data.jpa.repository.JpaRepository; 
 import org.springframework.data.jpa.repository.Query; 
 import org.springframework.data.repository.query.Param; 
 
公共接口GameRepository扩展了JpaRepository< Game，Long> {
 
 @Query（从g中选择g，GamePlatformMap gpm，Platform p其中g = gpm.game和gpm.platform = p和p.id =：platform）
 Page< ;游戏和GT; getGamesByPlatform（@Param（platform）long platformId，Pageable可分页）; 
 
 @Query（从g中选择g，其中g.title如：title）
 Page< Game> getGamesByTitle（@Param（title）字符串标题，Pageable可分页）; 
 
 @Query（从g中选择g，GameGenreMap ggm，Genre ge，其中g = ggm.game和ggm.genre = ge和ge.id =：genreId）
 Page<游戏和GT; getGamesByGenre（@Param（genre）Long genreId，Pageable可分页）; 
} 
  

解决方案

我会说使用QueryDSL是你想做的一种方式。

例如，我有一个定义如下的库：

  public interface UserRepository扩展PagingAndSortingRepository< User，Long>，QueryDslPredicateExecutor< User> {
 
公共页面<用户> findAll（谓词谓词，Pageable p）; 
} 
  

我可以用任何参数组合来调用这个方法，如下所示： p>

  public class UserRepositoryTest {
 
 @Autowired 
 UserRepository userRepository; 
 
 @Test 
 public void testFindByGender（）{
 List< User> users = userRepository.findAll（QUser.user.gender.eq（Gender.M））; 
 Assert.assertEquals（4，users.size（））; 
 
 users = userRepository.findAll（QUser.user.gender.eq（Gender.F））; 
 Assert.assertEquals（2，users.size（））; 
 
 
 @Test 
 public void testFindByCity（）{
 
 List< User> users = userRepository.findAll（QUser.user.address.town.eq（Edinburgh））; 
 Assert.assertEquals（2，users.size（））; 
 
 users = userRepository.findAll（QUser.user.address.town.eq（Stirling））; 
 Assert.assertEquals（1，users.size（））; 
} 
 
 @Test 
 public void testFindByGenderAndCity（）{
 List< User> users = userRepository.findAll（QUser.user.address.town.eq（Glasgow）。and（QUser.user.gender.eq（Gender.M）））; 
 Assert.assertEquals（2，users.size（））; 
 
 users = userRepository.findAll（QUser.user.address.town.eq（Glasgow）。and（QUser.user.gender.eq（Gender.F）））; 
 Assert.assertEquals（1，users.size（））; 
} 
} 
  

I am looking for a solution to dynamically build queries using Spring Data JPA. I have a GameController which has a RESTful service endpoint /games which takes 4 optional parameters: genre, platform, year, title. The API may be passed none of those, all 4, and every combination in between. If any parameter is not passed it defaults to null. I need a method in the Repository that will build the appropriate query and ideally also still allow Spring Data JPA Paging, although I'm not sure if that is possible.

I found this article but this doesn't seem to be what I need unless I am misunderstanding. http://spring.io/blog/2011/04/26/advanced-spring-data-jpa-specifications-and-querydsl/

I know JPA has a Query Criteria API but really have no idea how to implement this.

I realize I could create a method for each possible scenario but that seems like really bad practice and a lot of unnecessary code.

GameRepository:

package net.jkratz.igdb.repository;

import net.jkratz.igdb.model.Game;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.Pageable;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.Query;
import org.springframework.data.repository.query.Param;

public interface GameRepository extends JpaRepository<Game, Long> {

    @Query("select g from Game g, GamePlatformMap gpm, Platform p where g = gpm.game and gpm.platform = p and p.id = :platform")
    Page<Game> getGamesByPlatform(@Param("platform") Long platformId, Pageable pageable);

    @Query("select g from Game g where g.title like :title")
    Page<Game> getGamesByTitle(@Param("title") String title, Pageable pageable);

    @Query("select g from Game g, GameGenreMap ggm, Genre ge where g = ggm.game and ggm.genre = ge and ge.id = :genreId")
    Page<Game> getGamesByGenre(@Param("genre") Long genreId, Pageable pageable);
}

解决方案

I would say that using QueryDSL is one way of doing what you want.

For example I have a repository defined as below:

public interface UserRepository extends PagingAndSortingRepository<User, Long>, QueryDslPredicateExecutor<User> {

    public Page<User> findAll(Predicate predicate, Pageable p);
}

I can call this method with any combination of parameters, like below:

public class UserRepositoryTest{

    @Autowired
    private UserRepository userRepository;

    @Test
    public void testFindByGender() {
        List<User> users = userRepository.findAll(QUser.user.gender.eq(Gender.M));
        Assert.assertEquals(4, users.size());

        users = userRepository.findAll(QUser.user.gender.eq(Gender.F));
        Assert.assertEquals(2, users.size());
    }

    @Test
    public void testFindByCity() {

        List<User> users = userRepository.findAll(QUser.user.address.town.eq("Edinburgh"));
        Assert.assertEquals(2, users.size());

        users = userRepository.findAll(QUser.user.address.town.eq("Stirling"));
        Assert.assertEquals(1, users.size());
    }

    @Test
    public void testFindByGenderAndCity() {
        List<User> users = userRepository.findAll(QUser.user.address.town.eq("Glasgow").and(QUser.user.gender.eq(Gender.M)));
        Assert.assertEquals(2, users.size());

        users = userRepository.findAll(QUser.user.address.town.eq("Glasgow").and(QUser.user.gender.eq(Gender.F)));
        Assert.assertEquals(1, users.size());
    }
}

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