Why am I getting null values on the server side after sending a post request by Postman

Question

I have created a Restfull webservice using spring boot to add a record to H2 database but when I send data from postman to my handler method I get null values on the server side and on the response sent to the client side as well, could anybody help me? [P My Eclipse console snapshot ostman snapshot] 2

My Controller:

@RestController
public class AlienController {

    @Autowired
    AlienRepo repo;
    
    @RequestMapping("/")
    public String home() {
        return"home.jsp";
    }
    
    @PostMapping(path="/alien")
    public Alien addAlien(Alien alien) {
        System.out.println(alien);
        repo.save(alien);
        return alien;
    }
    

My DAO Class:

    @Entity
    public class Alien {
    
        @Id
        @GeneratedValue(strategy = GenerationType.IDENTITY)
        private int aid;
        private String aname;
        private String lang;
        
        public int getAid() {
            return aid;
        }
        public void setAid(int aid) {
            this.aid=aid;       
        }
        
        public String getAname() {
            return aname;
        }
        public void setAname(String aname) {
            this.aname=aname;       
        }
        
        public String getLang() {
            return lang;
        }
        public void setLang(String lang) {
            this.lang=lang;         
        }
        @Override
        public String toString() {
            return "Alien Info: Aid=" + aid + ", Aname=" + aname + ", Lang=" +lang;
        }       
    }
    

My AlienRepository:

    public interface AlienRepo extends JpaRepository<Alien, Integer>{   
    }

Answer 1

You should use the annotation @RequestBody:

   public Alien addAlien(@RequestBody Alien alien)

You should inform Spring that you are waiting for a HttpRequest that contains a Body, Spring will automatically deserialize the inbound HttpRequest body onto Java object.