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

我有两个班级Flight和Ticket. 一个航班可以有很多票，所以Ticket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，但我无法将其保存到我的数据库中，我遇到了这样的错误：

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

班级票：

@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

类票证Dto：

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

我的班级航班：

@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

我的班级 FlightDto：

public class FlightDto {
private int flight_id;

//

private List<TicketDto> ticket;

// getters setters

这是带有保存我的票证的方法的 TicketServiceImpl 类：

@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 中的类 ticket.ts：

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

Answer 1

它需要您的 dto 类中的 int flight_id 。将 flight_id 类型的类型更改为 Integer 并在 TickerDTO 类中添加另一个 Flight 引用。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，如果您不想更改您的 ticketDto 类，请将您的 json 更改为：

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