JSON 序列化程序如何忽略导航属性

在进行 JSON 序列化时，有时候我们希望忽略实体对象中的导航属性，即不将其包含在最终生成的 JSON 字符串中。导航属性通常用于在实体对象之间建立关联关系，例如一个订单对象可能包含一个指向客户对象的导航属性。然而，在某些情况下，我们并不想在序列化过程中包含这些导航属性，因为它们可能包含大量的数据或者会导致循环引用的问题。本文将介绍如何使用不同的编程语言和框架来实现忽略导航属性的 JSON 序列化。

csharp
public class Order
{
    public int Id { get; set; }
    public string CustomerName { get; set; }
    [JsonIgnore]
    public Customer Customer { get; set; }
}
public class Customer
{
    public int Id { get; set; }
    public string Name { get; set; }
}
var order = new Order
{
    Id = 1,
    CustomerName = "John Doe",
    Customer = new Customer { Id = 1, Name = "John Doe" }
};
var json = JsonConvert.SerializeObject(order);
Console.WriteLine(json);

java
public class Order {
    private int id;
    private String customerName;
    private Customer customer;
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getCustomerName() {
        return customerName;
    }
    public void setCustomerName(String customerName) {
        this.customerName = customerName;
    }
    @JsonIgnore
    public Customer getCustomer() {
        return customer;
    }
    public void setCustomer(Customer customer) {
        this.customer = customer;
    }
}
public class Customer {
    private int id;
    private String name;
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
}
Order order = new Order();
order.setId(1);
order.setCustomerName("John Doe");
Customer customer = new Customer();
customer.setId(1);
customer.setName("John Doe");
order.setCustomer(customer);
ObjectMapper objectMapper = new ObjectMapper();
String json = objectMapper.writeValueAsString(order);
System.out.println(json);