Spring Data: Could not determine type for: java.util.List, at table: user, for columns: [org.hibernate.mapping.Column(roles)] - spring-boot

Question

I am new to Spring, and I was following this tutorial Spring Rest Services
to understand how oAuth works with REST APIs.
Prior to this, my app was running smoothly.
While working with the tutorial, it required me to have my User entity implement UserDetails. And I had to add an extra List<String> roles because it is used in my UserDetailsImpl service which implements UserDetailsService.
And now when I run mvn spring-boot:run I get the error that's mentioned in the title.
I looked up online, but most of the issues were related to table associations via a particular column, but in my code, there is no type of association mapped to/from roles column.
Here is my User entity:
#Entity
public class User implements UserDetails {
#Id
private UUID id;
private String name;
private String email;
private String password;
private List<String> roles;
public User (){
}
public User (String email, String name, String password, UUID id, List<String> roles){
this.email = email;
this.name = name;
this.password = password;
this.id = id;
this.roles = roles;
}
public String getEmail() {
return email;
}
public String getName() {
return name;
}
#Override
public Collection<? extends GrantedAuthority> getAuthorities() {
return null;
}
#Override
public String getPassword() {
return password;
}
#Override
public String getUsername() {
return email;
}
#Override
public boolean isAccountNonExpired() {
return false;
}
#Override
public boolean isAccountNonLocked() {
return false;
}
#Override
public boolean isCredentialsNonExpired() {
return false;
}
#Override
public boolean isEnabled() {
return false;
}
public UUID getId() {
return id;
}
List<String> getRoles() {
return roles;
}
public void setPassword(String password) {
this.password = password;
}
public void setEmail(String email) {
this.email = email;
}
public void setName(String name) {
this.name = name;
}
public void setId(UUID id) {
this.id = id;
}
}
And this my UserDetailsImp service:
#Service
public class UserDetailsImp implements UserDetailsService {
#Autowired
UserRepository userRepository;
#Override
public UserDetails loadUserByUsername(String email) throws UsernameNotFoundException {
User user = userRepository.getOneByEmail(email);
UserBuilder builder = null;
if( user != null){
builder.username(user.getEmail()).password(user.getPassword()).roles(String.join("",user.getRoles()));
} else {
throw new UsernameNotFoundException("User not found");
}
return builder.build();
}
}
Any help would be hugely appreciated.

Answer 1

The field private List<String> roles has unknown type in the DB.
Try using #ElementCollection annotation.
https://docs.oracle.com/javaee/6/api/javax/persistence/ElementCollection.html