Spring Data failed to lazily initialize a collection of role, could not initialize proxy - no Session

I am making an API with Spring Boot and I never seem to manage to initialize lazy collections. The only solution that has ever worked for me is changing it to eager, but that is no solution.

@Entity
@Getter
@Setter
@NoArgsConstructor
@Table(name = "user")
public class UserEntity {
@Id
@GeneratedValue
private Long id;
@Column(unique = true)
String email;
@ElementCollection(fetch = LAZY)
List<String> roles = new ArrayList<>();
public UserEntity(String email) {
this.email = email;
}
}

@Order(Ordered.LOWEST_PRECEDENCE)
@Component
public class AuthFilter extends OncePerRequestFilter {
Logger LOG = LoggerFactory.getLogger(AuthFilter.class);
@Autowired
UserRepository userRepository;
@Override
@Transactional
protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain)
throws ServletException, IOException {
Authentication authentication = SecurityContextHolder.getContext().getAuthentication();
if(authentication != null && authentication.isAuthenticated()){
String email = authentication.getName();
UserEntity user = userRepository.findByEmail(email).orElse(new UserEntity(email));
user.getRoles().clear();
user.getRoles().addAll(authentication.getAuthorities().stream().map(GrantedAuthority::getAuthority).collect(Collectors.toSet()));
userRepository.save(user);
}
filterChain.doFilter(request, response);
}
}

These are my two classes. A user entity and a filter that will create user from an authentication object. When the line user.getRoles().clear(); is called, I get the famous error org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: ch.ciip.ressources.api.user.UserEntity.roles, could not initialize proxy - no Session.

From my understanding, Spring Data will create a proxy for each lazy relation, and will only fetch the data once it is accessed. But to access it it needs a session and apparently, Spring is not able to create a session when accessing a proxy, however, it has no problem doing it when I call save on a repository.

What I've tried is :

• @Transactional from both org.springframework.transaction.annotation.Transactional and javax.transaction.Transactional. But it changes absolutely nothing.
• Change fetch type to EAGER. This method works, but it is not what I want to do.
• Change enable_lazy_load_no_trans=trueto true in application.properties file. This method is not recommended, so I will not try it.
• Calling a method on the lazy collection before trying to modify it. For example calling user.getRoles().size(); so it gets initialized. But it does not work.
• Calling Hibernate.initialize(user.getRoles()); to initialize the collection. But it does not work.

I wonder why Spring says No Session because it does create a session for the userRepository.findByEmail(email) as well as for userRepository.save(user).

I could create an entitymanager manually and use it to fetch/persist my entities. But that is not the goal as I'm using Spring Data JPA.

Make the method public, i.e.:

@Override
@Transactional
public void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain)
throws ServletException, IOException {
Authentication authentication = SecurityContextHolder.getContext().getAuthentication();
if(authentication != null && authentication.isAuthenticated()){
String email = authentication.getName();
UserEntity user = userRepository.findByEmail(email).orElse(new UserEntity(email));
user.getRoles().clear();
user.getRoles().addAll(authentication.getAuthorities().stream().map(GrantedAuthority::getAuthority).collect(Collectors.toSet()));
userRepository.save(user);
}
filterChain.doFilter(request, response);
}

Creating a separate service class and injecting it into this filter is a workaround i can propose.

@Service
class UserService {
@Autowired
private UserRepository userRepository;
@Transactional
public void findUserByEmailAndAddRoles(String email, Set<String> authorities) {
UserEntity user = userRepository.findByEmail(email)
.orElse(new UserEntity(email));
user.getRoles().clear();
user.getRoles().addAll(authorities);
userRepository.save(user);
}
}

Then use this in your filter

@Override
protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain)
throws ServletException, IOException {
Authentication authentication = SecurityContextHolder.getContext().getAuthentication();
if(authentication != null && authentication.isAuthenticated()){
String email = authentication.getName();
Set<String> authorities = authentication.getAuthorities().stream()
.map(GrantedAuthority::getAuthority).collect(Collectors.toSet());
userService.findUserByEmailAndAddRoles(email, authorities);
}
filterChain.doFilter(request, response);
}