從嵌套列表Spring JpaRepository中檢索對象

Question

我有一個存儲庫

public interface GroupRepository extends JpaRepository<Group, Integer> {
}

該集團確實有一個項目清單

private List<Item> items;

每個物品都有一個位置屬性

private int position;

如何通過了解其中一個列表中的項目位置來檢索組 ？

Item.java

public class Item extends PersistedBean{
 private int position;
 private Group group;

 @Column(name = "Position")
  public int getPosition() {
    return position;
  }

  @ManyToOne(fetch = FetchType.EAGER)
  @JoinColumn(name = "GroupId", referencedColumnName = "Id")
  public Group getGroup() {
    return group;
  }
}

Group.java

public class Group extends PersistedBean {
 private int position;
 private List<Item> items;

  @Column(name = "Position")
  public int getPosition() {
    return position;
  }

  @OneToMany(cascade = CascadeType.ALL, mappedBy = "group", orphanRemoval = false)
  public List<Item> getItems() {
    return items;
  }

}

Answer 1

您可以向JpaRepository<Group, Integer>存儲庫添加查詢，類似應該工作：

@Query("SELECT g FROM Group g " + 
       "JOIN g.items i ON i.position IN :p")
List<Group> getGroupsWhenPositionMatchAnyRelatedItem(@Param("p") Integer p);