Spring Boot - "this.peopleService" is null?-CodePudding

I'm a bit new to Spring Boot and I'm trying to create model/repo/service/serviceImp/controller type of architecture.

After I try to make a this get request:

http://localhost:8080/api/v1/people/name?name=steve

and I get this error (I created a couple of people in DB):

"java.lang.NullPointerException: Cannot invoke \"com.project.Springbootbackend.service.PeopleService.findAllByName(String)\" because \"this.peopleService\" is null\r\n\tat com.project.Springbootbackend.controller.PeopleController.findAllByName(PeopleController.java:24)

This is my code: People(entity)

@Entity
public class People {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long id;

    @Column(name = "name")
    private String name;

    @Column(name = "surname")
    private String surname;

    @Column(name = "email")
    private String email;
...
//constructor   get/set

PeopleController

@RestController
@RequestMapping("/api/v1/people")
@RequiredArgsConstructor
public class PeopleController {

    private PeopleService peopleService;

    @GetMapping("/name")
    public ResponseEntity<List<People>> findAllByName(@RequestParam String name) {

        return ResponseEntity.ok().body(peopleService.findAllByName(name));
    }
}

PeopleRepo

public interface PeopleRepository extends JpaRepository<People, Integer> {
    List<People> findAllByName(String name);
}

PeopleService

public interface PeopleService {
    List<People> findAllByName(String name);

}

PeopleServiceImp

@RequiredArgsConstructor
@Service
public class PeopleServiceImp implements PeopleService {

    PeopleRepository peopleRepository;

    @Override
    public List findAllByName(String name) {
        return (List) ResponseEntity.ok(peopleRepository.findAllByName(name));
    }

}

Thx guys in advance.

*SOLUTION:

Entity, service & repository is the same. ServiceImp and controller changes are down belowe:

Controller:

@RestController
@RequestMapping("/api/v1/people")
public class PeopleController {

    private PeopleService peopleService;

    public PeopleController(PeopleService peopleService) {
        this.peopleService = peopleService;
    }

    @GetMapping("/name")
    public ResponseEntity<List<People>> findAllByName(@RequestParam String name) {

        return ResponseEntity.ok().body(peopleService.findAllByName(name));
    }
}

ServiceImp

@Service
public class PeopleServiceImp implements PeopleService {

    private PeopleRepository peopleRepository;

    public PeopleServiceImp(PeopleRepository peopleRepository) {
        this.peopleRepository = peopleRepository;
    }

    @Override
    public List<People> findAllByName(String name) {
        List<People> people = peopleRepository.findAllByName(name);
        return people;
    }

}

CodePudding user response：

Your constructor does not inject the service, because of the RequiredArgsConstructor (see Link) needs special treatment. Therefore, use final:

@RestController
@RequestMapping("/api/v1/people")
@RequiredArgsConstructor
public class PeopleController {

    private final PeopleService peopleService;

    @GetMapping("/name")
    public ResponseEntity<List<People>> findAllByName(@RequestParam String name) {

        return ResponseEntity.ok().body(peopleService.findAllByName(name));
    }
}

Same here:

@RequiredArgsConstructor
@Service
public class PeopleServiceImp implements PeopleService {

    private final PeopleRepository peopleRepository;

    @Override
    public List findAllByName(String name) {
        return (List) ResponseEntity.ok(peopleRepository.findAllByName(name));
    }

}

Additional hint, use a typed list:

@Override
public List<People> findAllByName(String name) {
    return ResponseEntity.ok(peopleRepository.findAllByName(name));
}

CodePudding user response：

Try like this:

@Autowired
private PeopleService peopleService;

@Autowired
private PeopleRepository peopleRepository;

You also need to add the @SpringBootApplication annotation in the main class of the application.

Something like that:

@SpringBootApplication
class PeopleApplication {
public static void main(String[] args) {
...

Take a look at this article about automatic dependency injection in Spring: https://www.baeldung.com/spring-autowire

CodePudding user response：

You missed the autowiring annotation in the controller to inject the service which may make this.peopleService to be null.

@Autowired
private PeopleService peopleService;