How to write custom queries in spring CRUD Repository - spring-boot

Question

I am developing an app using spring Boot.
Here is my code.
UserSample.java
#Entity
public class UserSample {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private long userId;
private String userName;
public UserSample() {
super();
}
public UserSample(String userName) {
super();
this.userName = userName;
}
public long getUserId() {
return userId;
}
public void setUserId(long userId) {
this.userId = userId;
}
public String getUserName() {
return userName;
}
public void setUserName(String userName) {
this.userName = userName;
}
}
Interface is:
public interface UserSampleRepository extends CrudRepository<UserSample, Long> {
}
In main class
#SpringBootApplication
public class MainApplication implements CommandLineRunner {
#Autowired
UserSampleRepository usersampleRepo;
public static void main(String[] args) {
SpringApplication.run(MainApplication.class, args);
}
#Override
public void run(String... args) throws Exception {
List<UserSample> userSample = new LinkedList<UserSample>();
// load data to the table
userSample.add(new UserSample("user1"));
userSample.add(new UserSample("user2"));
usersampleRepo.save(userSample);
UserSample userInfo = usersampleRepo.findOne(1);
}
}
I am having in-memory database. Here I am trying to write a query to retrieve by username. like userSampleRepo.findByUserName(String username);
I tried many ways but nothing worked for me.any suggestions?
I tried adding a method in interface .
public interface UserSampleRepository extends CrudRepository<UserSample, Long> {
UserSample findByUserName(String username);
}
created another class.
#Repository
public class UserSampleRepositoryImpl implements UserSampleRepository {
#PersistenceContext
private EntityManager em;
#Override
public UserSample findByUserName(String username) {
TypedQuery<UserSample> query = em.createQuery("select c from UserSample c where c.userName = :username",
UserSample.class);
query.setParameter("username", username);
return query.getSingleResult();
}
In main class, I used this statement
#Autowired
UserSampleRepositoryImpl usersampleRepo;
UserSample userInfo = usersampleRepo.findByUserName("user1");
I am getting this error:
"java.lang.IllegalStateException: Failed to execute CommandLineRunner"
aused by: org.springframework.dao.EmptyResultDataAccessException: No entity found for query; nested exception is javax.persistence.NoResultException: No entity found for query