Hibernate, Relacje pomiędzy encjami

@Entity
@Table(name="activation_code")
public class ActivationCode {
	
	@Id
	@GeneratedValue(strategy=GenerationType.IDENTITY)
	@Column(name="id_activation_code")
	private int id_activation_code;
	
	@Column(name="serial_number")
	private String serial_number;
	
	@OneToOne(mappedBy="id_activation_code", cascade= {CascadeType.DETACH,
			 										   CascadeType.MERGE,
			 										   CascadeType.PERSIST,
			 										   CascadeType.REFRESH })
	private User user;
	
	
	
	public ActivationCode() {
		
	}
}

@Entity
@Table(name="user")
public class User {
	
	@Id
	@GeneratedValue(strategy=GenerationType.IDENTITY)
	@Column(name="id_user")
	private int id_user;
	
	@OneToOne(cascade={CascadeType.DETACH,
						CascadeType.MERGE,
						CascadeType.PERSIST,
						CascadeType.REFRESH})
	@JoinColumn(name="id_activation_code")
	private ActivationCode id_activation_code;

	@Column(name="user_name")
	private String user_name;
	
	@Column(name="user_surname")
	private String user_surname;
	
	@Column(name="user_email")
	private String user_email;
	
	@Column(name="user_password")
	private String user_password;
	
	@Column(name="user_phone_number")
	private String user_phone_number;
	
	@Column(name="user_car")
	private String user_car;
	
	@Column(name="user_description")
	private String user_description;
	
	@Column(name="is_active")
	private boolean is_active;
	
	@OneToMany(mappedBy="id_user",
			cascade= {CascadeType.PERSIST, CascadeType.MERGE,
					  CascadeType.DETACH, CascadeType.REFRESH})
	private List<Seat> listOfUserSeats;
	
	public User() {
		
	}
}

{
    "serverResponse": {
        "msg": "Code exist in database",
        "succesful": true
    },
    "activationCode": {
        "id_activation_code": 1,
        "serial_number": "abcd",
	"id_user" : 3
    }
}

"{\"id_activation_code\":3,\"serial_number\":\"asdf\",\"user\":{\"id_user\":5,\"user_name\":\"testowanie update u\",\"user_surname\":\"testowanie update u\",\"user_email\":\"test\",\"user_password\":\"test\",\"user_phone_number\":\"test\",\"user_car\":\"test\",\"user_description\":\"test\",\"is_active\":true}}"

mapper.enable(SerializationFeature.INDENT_OUTPUT);

 mapper.writerWithDefaultPrettyPrinter()

	public static String serializeObjectToString(Object object, Class<?> serializationView)
			throws JsonProcessingException {
		ObjectMapper mapper = new ObjectMapper();
		mapper.disable(MapperFeature.DEFAULT_VIEW_INCLUSION);
		String result = mapper.writerWithView(serializationView).writeValueAsString(object);
		return result;
	}

	public static Object deserializeStringToObject(String jsonString, Class<?> view, Class<?> valueType)
			throws JsonProcessingException, IOException {
		ObjectMapper mapper = new ObjectMapper();
		Object object = mapper.readerWithView(view).forType(valueType).readValue(jsonString);
		return object;
	}

    public static String serializeObjectToString(Object object, Class<?> serializationView) throws JsonProcessingException {
        ObjectMapper mapper = new ObjectMapper()
                .enable(SerializationFeature.INDENT_OUTPUT)
                .disable(MapperFeature.DEFAULT_VIEW_INCLUSION);

        return mapper.writerWithView(serializationView).writeValueAsString(object);
    }

package borgwarner.com.pickmeup.rest;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.bind.annotation.RestController;

import com.fasterxml.jackson.core.JsonProcessingException;

import borgwarner.com.pickmeup.entity.ActivationCode;
import borgwarner.com.pickmeup.jsonhelper.JsonViewSerializeUtils;
import borgwarner.com.pickmeup.jsonhelper.View;
import borgwarner.com.pickmeup.responses.ActivationCodeResponse;
import borgwarner.com.pickmeup.service.ActivationCodeService;


@RestController
@RequestMapping("/api")
public class ActivationCodeRestController {

	private ActivationCodeService activationCodeService;
	
	@Autowired
	public ActivationCodeRestController(ActivationCodeService activationCodeService) {
		this.activationCodeService = activationCodeService;
	}
	
	@GetMapping("/activationcodes")
	public List<String> findAll(){
		List<ActivationCode> listOfActivationCodes = activationCodeService.findAll();
		List<String> listOfAllActivationCodesAfterSerializing = new ArrayList<>();
		String result = "";	
		for (ActivationCode activationCode : listOfActivationCodes) {
			try {
				result = JsonViewSerializeUtils.serializeObjectToString(activationCode, View.ActivationCode.class);
			} catch (JsonProcessingException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
			listOfAllActivationCodesAfterSerializing.add(result);
		}
		return listOfAllActivationCodesAfterSerializing;
	}

	@GetMapping("/activationcodes/serialnumber")
	@ResponseBody
	public ActivationCodeResponse findActivationCodeBySerialNumber(@RequestParam String serialNumber) {
		return activationCodeService.findActivationCodeBySerialNumber(serialNumber);	
	}
	
	@GetMapping("/activationcodes/{theID}")
	public ActivationCodeResponse findActivationCodeByID(@PathVariable int theID) {
		return activationCodeService.findActivationCodeByID(theID);
	}	
	
}

    @GetMapping("/activationcodes")
    @JsonView(View.ActivationCode.class)
    public List<ActivationCode> findAll() {
        return activationCodeService.findAll();
    }

@Entity
@Table(name="offered_ride")
public class OfferedRide {
	
	@Id
	@GeneratedValue(strategy=GenerationType.IDENTITY)
	@Column(name="id_offered_ride")
	@JsonView({View.User.class, View.ActivationCode.class, View.OfferedRide.class})
	private int id_offered_ride;

	@Column(name="date_of_ride")
	@JsonView({View.User.class, View.ActivationCode.class, View.OfferedRide.class})
	private Date date_of_ride;
	
	@Column(name="time_of_ride")
	@JsonView({View.User.class, View.ActivationCode.class, View.OfferedRide.class})
	private Time time_of_ride;
	
	@Column(name="number_of_free_seats")
	@JsonView({View.User.class, View.ActivationCode.class, View.OfferedRide.class})
	private int number_of_free_seats;
	
	@Column(name="ride_category")
	@JsonView({View.User.class, View.ActivationCode.class, View.OfferedRide.class})
	private int ride_category;
	
	@Column(name="from_where")
	@JsonView({View.User.class, View.ActivationCode.class, View.OfferedRide.class})
	private String from_where;
	
	@Column(name="to_where")
	@JsonView({View.User.class, View.ActivationCode.class, View.OfferedRide.class})
	private String to_where;
	
	@Column(name="user_comment")
	@JsonView({View.User.class, View.ActivationCode.class, View.OfferedRide.class})
	private String user_comment;
	
	@ManyToOne(cascade= {CascadeType.PERSIST, CascadeType.MERGE,
			CascadeType.DETACH, CascadeType.REFRESH})
	@JoinColumn(name="id_user")
	@JsonView({View.OfferedRide.class})
	private User user;
	
	@OneToMany(mappedBy="offeredRide",
			cascade= CascadeType.ALL)
	@JsonView({View.User.class, View.ActivationCode.class, View.OfferedRide.class})
	private List<Seat> listOfSeats;
	
	public OfferedRide() {
		
	}

@Entity
@Table(name="user")
public class User {
	
	@Id
	@GeneratedValue(strategy=GenerationType.IDENTITY)
	@Column(name="id_user")
	@JsonView({View.User.class, View.ActivationCode.class})
	private int id_user;
	
	@OneToOne(cascade={CascadeType.DETACH,
			 CascadeType.MERGE,
			 CascadeType.PERSIST,
			 CascadeType.REFRESH })
	@JoinColumn(name="id_activation_code")
	@JsonView({View.User.class})
	private ActivationCode activationCode;

	@Column(name="user_name")
	@JsonView({View.User.class, View.ActivationCode.class, View.OfferedRide.class})
	private String user_name;
	
	@Column(name="user_surname")
	@JsonView({View.User.class, View.ActivationCode.class, View.OfferedRide.class})
	private String user_surname;
	
	@Column(name="user_email")
	@JsonView({View.User.class, View.ActivationCode.class, View.OfferedRide.class})
	private String user_email;
	
	@Column(name="user_password")
	@JsonView({View.User.class, View.ActivationCode.class, View.OfferedRide.class})
	private String user_password;
	
	@Column(name="user_phone_number")
	@JsonView({View.User.class, View.ActivationCode.class, View.OfferedRide.class})
	private String user_phone_number;
	
	@Column(name="user_car")
	@JsonView({View.User.class, View.ActivationCode.class, View.OfferedRide.class})
	private String user_car;
	
	@Column(name="user_description")
	@JsonView({View.User.class, View.ActivationCode.class, View.OfferedRide.class})
	private String user_description;
	
	@Column(name="is_active")
	@JsonView({View.User.class, View.ActivationCode.class, View.OfferedRide.class})
	private boolean is_active;
	
	@OneToMany(mappedBy="user",
			cascade= {CascadeType.PERSIST, CascadeType.MERGE,
					  CascadeType.DETACH, CascadeType.REFRESH})
	@JsonView({View.User.class, View.ActivationCode.class})
	private List<OfferedRide> listOfOfferedRides;
	
	public User() {
		
	}

	@Id
	@GeneratedValue(strategy=GenerationType.IDENTITY)
	@Column(name="id_seat")
	private int id_seat;
	
	@ManyToOne(cascade= {CascadeType.PERSIST, CascadeType.MERGE,
			CascadeType.DETACH, CascadeType.REFRESH})
	@JoinColumn(name="id_offered_ride")
	@JsonView({View.Seat.class})
	private OfferedRide offeredRide;
	
	@ManyToOne(cascade= {CascadeType.PERSIST, CascadeType.MERGE,
			CascadeType.DETACH, CascadeType.REFRESH})
	@JoinColumn(name="id_user")
	@JsonView({View.Seat.class})
	private User id_user;
	
	public Seat() {
		
	}

    @ManyToOne(cascade= {CascadeType.PERSIST, CascadeType.MERGE,
            CascadeType.DETACH, CascadeType.REFRESH})
    @JoinColumn(name="id_offered_ride")
    @JsonView({View.Seat.class, View.ActivationCode.class})
    private OfferedRide offeredRide;