Implementing query "findByUsername" on Spring Boot-CodePudding

So, I´m currently on project where I have to create my own repositories without extending Jpa or CRUD repositories, i would like to know how I can implement the same method found in JpaRepository called "findByUsername" to work the same way. It receives a String and returns the whole Object in case it finds the username in the DB.

This is my UserDao

public interface UserDAO extends AbstractDAO<User, Long>{
User findByUsername (String username);
}

And this is my This is my UserDaoImplements there I need to implement the body of the method findByUsername:

@Repository
public class UserDAOImpl extends AbstractDAOImpl<User, Long> implements UserDAO {

@Override
public User findByUsername(String username) {
    return null;
}
}

CodePudding user response：

As you have annotated your question with hibernate, I am suggesting to use EntityManager :

public class UserDAOImpl extends AbstractDAOImpl<User, Long> implements UserDAO {
@Autowired
EntityManager em;

@Override
public User findByUsername(String username) {
    Query q = em.createNativeQuery("select * from User where username = :username", User.class);
     q.setParameter("username", username);
     return (User)q.getSingleResult();
}
}