如何从Number值反序列化为int（错误-没有从Number值反序列化的int / Int参数构造函数/工厂方法）

Question

我有两个班Flight和Ticket。一次航班可以有很多票，因此Ticket具有外键flight_id。

这是我的数据库，其中包含表flight和ticket。

这是我的json request（来自Mozilla调试器），我想将其保存在数据库中。

您可以看到flight_id参数，但是我无法将其保存到数据库中，但出现了这样的错误：

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 of模型。飞行(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 of模型。飞行(although at least one Creator exists): no int/Int-argument constructor/factory method to deserialize from Number value

机票：

@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

TicketDto类：

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

我班的航班：

@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

我的班机FlightDto：

public class FlightDto {
private int flight_id;

//

private List<TicketDto> ticket;

// getters setters

这是TicketServiceImpl类，其中包含保存我的票证的方法：

@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);
}

我在Angular中的班票.ts

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

Answer 1

它在您的dto类中期望一个int flight_id。将flight_id类型的类型更改为Integer，然后在TickerDTO类中添加另一个Flight参考。请尝试以下将其转换为Flight对象：

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);
}

或者如果您不想更改ticketDto类，请将json更改为：

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

Answer 2

您需要使用@JsonCreator在Flight中创建构造函数：

@JsonCreator
public Flight (@JsonProperty("flight_id") Integer flight_id ) {
    this.flight_id = flight_id;
}