根据 setter 中另一个属性的值更新类属性

Question

我有两个模型类：

public class Person
{
    public int PersonId { get; set; }
    public string Name { get; set; }
    public int AddressId { get; set; }
    public Address AddressInfo { get; set; }
}

public class Address
{
    public int AddressId { get; set; }
    public string streetName { get; set; }
    public string City { get; set; }
    public string State { get; set; }
}

如果任何值在Person.AddressInfo.AddressId中得到更新，我如何自动更新Person.AddressId ？

Answer 1

那这个呢？

public class Person
{
    public int PersonId { get; set; }
    public string Name { get; set; }
    public int AddressId 
    { 
        get{ return AddressInfo?.AddressId ?? 0 } 
        set{ AddressInfo?.AddressId = value; }
    }
    public Address AddressInfo { get; set; }
}

public class Address
{
    public int AddressId { get; set; }
    public string streetName { get; set; }
    public string City { get; set; }
    public string State { get; set; }
}

这使用 AddressInfo 作为后台存储

Answer 2

您可以简单地将以下内容写入 Person 类：

 public int AddressId{
    get{return this.AddressInfo?.AddressId ?? 0;}
    set{this.AddressInfo?.AddressId= value;}
 }

或者更好地写：

 public int? AddressId{
    get{return this.AddressInfo?.AddressId;}
    set{this.AddressInfo?.AddressId= value;}
 }

Answer 3

下面的代码可以帮助你，

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApplication5
{
    class Program
    {
        static void Main(string[] args)
        {
            Address test = new Address();
            test.AddressId = 0;
            test.City = "xyzzzzzzzzzzzzzzz";
            test.streetName = "xyz";
            test.State = "xyzzzzzzzzzzzzzzzxxxxxxxxxxxxxxxxxxx";

            Person ptest = new Person
            {
                PersonId = 1,
                Name = "test1",
                AddressInfo = test,
                AddressId = 5,
            };
        }
    }

    public class Address
    {
        public int AddressId { get; set; }
        public string streetName { get; set; }
        public string City { get; set; }
        public string State { get; set; }
    }
    public class Person
    {
        public int PersonId { get; set; }
        public string Name { get; set; }
        public int AddressId { 

            get{ return AddressInfo != null ? AddressInfo.AddressId : 0;}
            set { AddressInfo.AddressId = value; }
    }
        public Address AddressInfo { get; set; }
    }
}

在给 addressid 赋值之前确保 addressinfo 不为 null，如果它的 null 将数据分配给 addressinfo 那么你可以更新该值，否则你会得到对象引用错误。