I want to write a query like SELECT * FROM Release_date_type a LEFT JOIN cache_media b on a.id=b.id
. I am new to Spring Data JPA. I don't know how to write entities for Join query. Here is an attempt:
@Entity
@Table(name = "Release_date_type")
public class ReleaseDateType {
@Id
@GeneratedValue(strategy=GenerationType.TABLE)
private Integer release_date_type_id;
// ...
@Column(nullable = true)
private Integer media_Id;
// with getters and setters...
}
Another entity is:
@Entity
@Table(name = "Cache_Media")
public class CacheMedia {
@Id
@GeneratedValue(strategy=GenerationType.TABLE)
private Integer id;
// ...
private Date loadDate; //with the getter and setter ..
}
I want to write a crudRepository
interface such as
public interface ReleaseDateTypeRepository extends CrudRepository<ReleaseDateType, Long>{
@Query("SELECT * FROM Release_date_type a LEFT JOIN cache_media b on a.id=b.id")
public List<ReleaseDateType> FindAllWithDescriptionQuery();
}
For a typical example of employees owning one or more phones, see this wikibook section.
For your specific example, if you want to do a one-to-one
relationship, you should change the next code in ReleaseDateType model:
@Column(nullable = true)
private Integer media_Id;
for:
@OneToOne(fetch = FetchType.LAZY)
@JoinColumn(name="CACHE_MEDIA_ID", nullable=true)
private CacheMedia cacheMedia ;
and in CacheMedia model you need to add:
@OneToOne(cascade=ALL, mappedBy="ReleaseDateType")
private ReleaseDateType releaseDateType;
then in your repository you should replace:
@Query("Select * from A a left join B b on a.id=b.id")
public List<ReleaseDateType> FindAllWithDescriptionQuery();
by:
//In this case a query annotation is not need since spring constructs the query from the method name
public List<ReleaseDateType> findByCacheMedia_Id(Integer id);
or by:
@Query("FROM ReleaseDateType AS rdt WHERE cm.rdt.cacheMedia.id = ?1") //This is using a named query method
public List<ReleaseDateType> FindAllWithDescriptionQuery(Integer id);
Or if you prefer to do a @OneToMany
and @ManyToOne
relation, you should change the next code in ReleaseDateType model:
@Column(nullable = true)
private Integer media_Id;
for:
@OneToMany(cascade=ALL, mappedBy="ReleaseDateType")
private List<CacheMedia> cacheMedias ;
and in CacheMedia model you need to add:
@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name="RELEASE_DATE_TYPE_ID", nullable=true)
private ReleaseDateType releaseDateType;
then in your repository you should replace:
@Query("Select * from A a left join B b on a.id=b.id")
public List<ReleaseDateType> FindAllWithDescriptionQuery();
by:
//In this case a query annotation is not need since spring constructs the query from the method name
public List<ReleaseDateType> findByCacheMedias_Id(Integer id);
or by:
@Query("FROM ReleaseDateType AS rdt LEFT JOIN rdt.cacheMedias AS cm WHERE cm.id = ?1") //This is using a named query method
public List<ReleaseDateType> FindAllWithDescriptionQuery(Integer id);