Spring Data JPA Fetch from one table using the relationship table

Question

Here is my USER entity and USER_GROUP is a relation table with GROUP. How to fetch all Users Where groupid = ?

    @Entity 
    @Table(name="USER") 
    public class User implements Serializable {
      @Id Long userId;
      @ManyToOne 
      @JoinTable(name = "USER_GROUP", 
                joinColumns = @JoinColumn(name = "userid"), 
                inverseJoinColumns = @JoinColumn(name = "groupid")) 
      private List<Group> groups;
    } 

Answer 1

I believe you are using UserRepository as well. In your UserRepository you can write a method to fetch all such data.

public interface UserRepository extends JpaRepository<User, Long>{

    @Query(value="Select u from User u inner join u.groups group where group.groupid = :groupId ")
    List<User> findAllByGroupId(@Param("groupId") long groupId)

}

This should work. However i have not tested it.

Note Use DISTINCT to select only unique User objects.