How to deserialize from Number value to int (error - no int/Int-argument constructor/factory method to deserialize from Number value)

Question

I have two classes Flight and Ticket. One flight can has lots of tickets, so Ticket has foreign key flight_id.

Here is my database with tables flight and ticket.

Here is my json request (from Mozilla debugger), which I want to save in the database.

You can see flight_id parameter, but I can't save it to my database, I've got such an error:

at [Source: (PushbackInputStream); line: 1, column: 53] (through reference chain: dto.TicketDto["flight_id"]) DefaultHandlerExceptionResolver : Failed to read HTTP message: org.springframework.http.converter.HttpMessageNotReadableException: JSON parse error: Cannot construct instance ofmodel.Flight(although at least one Creator exists): no int/Int-argument constructor/factory method to deserialize from Number value (199); nested exception is com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot construct instance ofmodel.Flight(although at least one Creator exists): no int/Int-argument constructor/factory method to deserialize from Number value

Class Ticket:

@Entity
@Table(name = "ticket")
public class Ticket {

@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private int ticket_id;

@Column(name = "place")
private int place;

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

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

@JsonDeserialize(using = CustomParameterDeserializer.class)
@ManyToOne(targetEntity = Flight.class)
@JoinColumn(name = "flight_id")
@JsonBackReference("flight")
private Flight flight_id;

// getters setters
// constructor

Class TicketDto:

public class TicketDto {

private int ticket_id;

private int place;

private String name;

private String surname;

private Flight flight_id;

private Customer customer_id;

// getters setters

My class Flight:

@Entity
@Table(name = "flight")
public class Flight {

@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private int flight_id;

//

@OneToMany(mappedBy = "flight_id")
@JsonManagedReference("flight")
private List<Ticket> ticket;

// getters setters

My class FlightDto:

public class FlightDto {
private int flight_id;

//

private List<TicketDto> ticket;

// getters setters

Here is the class TicketServiceImpl with the method to save my Ticket:

@Service
public class TicketServiceImpl implements TicketService {

@Autowired
TicketRepository repository;

@Override
public Ticket save(TicketDto ticketDto) {
    Ticket ticket = new Ticket();
    ticket.setName(ticketDto.getName());
    ticket.setSurname(ticketDto.getSurname());
    ticket.setCustomer_id(ticketDto.getCustomer_id());
    ticket.setFlight_id(ticketDto.getFlight_id());
    ticket.setPlace(ticketDto.getPlace());

    return repository.save(ticket);
}

My class ticket.ts in Angular:

export class Ticket {
ticket_id: number;
place: string;
customer_id: number;
flight_id: number;
name: string;
surname: string;
}

Answer 1

It expects a int flight_id in your dto class. Change type of flight_id type to Integer and add another Flight reference in TickerDTO class. Try below to convert it into an Flight object:

public class TicketDto {
private int ticket_id;

private int place;

private String name;

private String surname;

private Flight flight;

private Customer customer_id;

@JsonProperty("flight_id")
private void unpackNested(Integer flight_id) {
    this.flight = new Flight();
    flight.setFlight_id(flight_id);
}

Or if you don't want to change your ticketDto class change your json to:

{
"name": "name",
"surname": "surname",
"flight_id": {
  "flight_id" : 123
}
}

Answer 2

for this error you have two possibilities to add in your class:

@JsonProperty("flight_id") private void unpackNested(Integer flight_id) {
    this.flight = new Flight(); flight.setFlight_id(flight_id);
}

but it's not the best way to do it because you don't modify a class like that without knowing the impacts behind it or doing all the necessary analyzes behind it

Or the second solution on the Data that you give to your DTO add this to you:

"flight_id":{
    "flight_id": id
}