java - Spring Boot JPA 多对一 - 根据关联的模型条件获取数据

Question

我有两个模型 - 图库和类别。

Category has many Gallery - @OneToMany

Gallery belongs to Gallery - @ManyToOne

Gallery.java

@Entity(name="Gallery")
public class Gallery {

    @ManyToOne
    @JoinColumn(name="category_id")
    private Category category;

    /* other code */
}

类别.java

@Entity(name="Category")
@Table(name="categories")
public class Category {
    @OneToMany(mappedBy="category")
    private Gallery gallery;
    /* other code */
}

GalleryRepository.java

@Repository("galleryRepository")
public interface GalleryRepository extends JpaRepository<Gallery, Long>, SiteInfoCustomRepository {

}

Question: How to fetch gallery data based on category title? I tried EntityManager and JOIN query but it's not returning in desired format.

GalleryService.java

@Override
public List<Gallery> getGallery(String cat) {
      // this works fine, fetches gallery and associated category
      galleryRepository.findAll();

      // I want to fetch gallery data which matches a particular category title

}

Answer 1

您只需在存储库中声明该方法，spring 就会为您创建查询。

Spring仅从方法的名称中推断出查询，如果你想按类别名称获取所有画廊，请像这样声明

@Repository("galleryRepository")
public interface GalleryRepository extends JpaRepository<Gallery, Long>, 
     SiteInfoCustomRepository {
    List<Gallery> findAllByCategoryName(String categoryName);
}

您可以从您的服务中调用此接口(interface)，例如:

@Service
public class GalleryService {

    @Autowired
    GalleryRepository galleryRepository;

    public List<Gallery> getGalleriesByCategoryName(String name) {
        return galleryRepository.findAllByCategoryName(name);
    }
}