Cannot invoke findByEmail because “this.userRepository” is null error

I keep receiving a Cannot invoke “com.***.repositories.UserRepository.findByEmail(String)” because “this.userRepository” is null error everytime I try to process my /register method.

I can’t figure out why the code is coming across as null.

Controller –

@Controller
@RestController
@RequestMapping("/api/v1")
@CrossOrigin(origins = "*", allowedHeaders = "*")
public class AuthenticationController {

    @Autowired
    UserService userService;
    UserRepository userRepository;
    AuthenticationTokenRepository authenticationTokenRepository;

    @PostMapping(value = "/register")
    public ModelAndView registerUser(ModelAndView modelAndView, User user) {
        User existingUser = userRepository.findByEmail(user.getEmail());
        if (existingUser != null) {
            modelAndView.addObject("message", "This email already exists!");
            modelAndView.setViewName("error");
        } else {
            userRepository.save(user);

            AuthenticationToken authenticationToken = new AuthenticationToken(user);
            authenticationTokenRepository.save(authenticationToken);

            SimpleMailMessage mailMessage = new SimpleMailMessage();
            mailMessage.setTo(user.getEmail());
            mailMessage.setSubject("Complete Registration!");
            mailMessage.setFrom("***@gmail.com");
            mailMessage.setText("To confirm your account, please click here : "
                    + "http://localhost:8080/confirm-account?token=" + authenticationToken.getConfirmationToken());

            emailSenderService.sendEmail(mailMessage);
            modelAndView.addObject("email", user.getEmail());
            modelAndView.setViewName("successfulRegisteration");
        }
        return modelAndView;
    }

}

Axios call –

submit() {
  let formData = new FormData();
  formData.set("firstName" , this.firstName)
  formData.set("lastName", this.lastName)
  formData.set("email", this.email)
  formData.set("password", this.password)
  formData.set("captchaToken", this.captchaToken)
  formData.set("agreedToTermsOfService", true)
  axios.post("http://localhost:8080/api/v1/register", formData,
      {headers: {'Content-Type': 'application/json'}})
      .then(res =>  {
        if (res.status === 200) {
          this.$router.push('/register-complete');
        } else {
          console.log(res.data.code);
        }
      })
      .catch(function (err) {
        console.log(err);
      })
}

My UserRepository –

@Repository
public interface UserRepository extends JpaRepository<User, Long> {
    User findByEmail(String email);
}

Answer

Simply add @Autowired to your related fields you want to get Autowired by spring.

Change your code from

   @Autowired
    UserService userService;
    UserRepository userRepository;
    AuthenticationTokenRepository authenticationTokenRepository;

to

   @Autowired
    UserService userService;

   @Autowired
    UserRepository userRepository;

   @Autowired
    AuthenticationTokenRepository authenticationTokenRepository;