java - Spring Security @AuthenticationPrincipal

Question

I've been trying to get @AuthenticationPrincipal to work properly with a custom User class. Unfortunately, the user is always null. Here's the code:

Controller

@RequestMapping(value = "/", method = RequestMethod.GET)
public ModelAndView index(@AuthenticationPrincipal User user) {
    ModelAndView mav= new ModelAndView("/web/index");
    mav.addObject("user", user);
    return mav;
}

Security Config

@Configuration
@EnableWebMvcSecurity
public class SecurityConfig extends WebSecurityConfigurerAdapter {

    @Autowired
    CustomUserDetailsService customUserDetailsService;

    @Autowired
    public void configureGlobal(AuthenticationManagerBuilder auth) throws Exception {
            auth.userDetailsService(customUserDetailsService).passwordEncoder(passwordEncoder());
    }

}

CustomUserDetailsService

@Component
public class CustomUserDetailsService implements UserDetailsService {

@Autowired
UserRepository userRepository;

@Override
public UserDetails loadUserByUsername(String username) throws UsernameNotFoundException {
    // Spring Data findByXY function
    return userRepository.findByUsername(username);
}

User Entity

public class User implements UserDetails{
    private String username;
    private String password;
    private Collection<Authority> authorities;

    // Getters and Setters

}

Authority Entity

public class Authority implements GrantedAuthority{
    private User user;
    private String role;

    // Getters and Setters

    @Override
    public String getAuthority() {
        return this.getRole();
    }
}

I've tried various solutions to this I found online, e.g. converting my custom user object like this:

return new org.springframework.security.core.userdetails.User(user.getLogin(), user.getPassword(), true, true, true, true,  authorities);

The other ways to get the active users are working without a problem, but I find the @AuthenticationProvider CustomUserObject to be the cleanest way, which is why I would like to get this to work. Any help is greatly appreciated.

Answer 1

Instead of using @AuthenticationPrincipal you can directly specify your dependency for authenticated user in method argument. something as given below

@RequestMapping(value = "/", method = RequestMethod.GET)
public ModelAndView index(Principal user) {
    ModelAndView mav= new ModelAndView("/web/index");
    mav.addObject("user", user);
    return mav;
} 

This Principal object will be actual object that got authenticated through spring security. Spring will inject this for you when the method will get invoked.