设置属性值

Question

我需要动态获取和设置一个属性值

我在c#中使用反射从字符串读取这个Get属性值

并执行下面的代码来获取值

public Object GetPropValue(Object obj, String name) {
    foreach (String part in name.Split('.')) {
        if (obj == null) { return null; }
        Type type = obj.GetType();
        PropertyInfo info = type.GetProperty(part);
        if (info == null) { return null; }
        obj = info.GetValue(obj, null);
    }
    return obj;
}

现在我需要将值设置为具有相同属性名称的其他对象

Employee emp1=new Employee();
var city=GetPropValue(emp1, "Address.City");
Need to set this city to other employee. Here Address is other class
emp1.GetType().GetProperty("Address.City").SetValue(emp2,city,null) //always sets null

但是没有设置。我怎样才能使一个通用setter方法，使这项工作简单?

Answer 1

这一行不对:

emp2.Address.City= emp1.GetType().GetProperty("Address.City").SetValue(emp2,city,null)

你试图将emp2.Address.City设置为调用给定对象的属性的setter的结果。

在这种情况下为什么要使用反射呢?给定你的代码行，你可以直接写

emp2.Address。城市=城市;

作为你的反射代码也设置了emp2的属性。因此，即使它成功了，它也会做同样的事情两次。

你的代码会像这样写:

emp2.Address.City = city;
emp1.GetType().GetProperty("Address.City").SetValue(emp2,city,null);

Answer 2

using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using System.Text;
using System.Threading.Tasks;
namespace LinqTests
{
    class Program
    {
        static void Main(string[] args)
        {
            var f1 = new F1 { F2 = new F2 { Name = "Test"}, Q = 10 };
            var f3 = new F3 { F2 = new F2() };
            Copier.Copy(f1, f3, "Q");
            Copier.Copy(f1, f3, "F2.Name");
        }
        static class Copier
        {
            public static void Copy(object source, object destination, string navigationPath)
            {
                var sourceValuePointHandle = GetValuePointHandle(source, navigationPath);
                var destinationValuePointHandle = GetValuePointHandle(destination, navigationPath);
                destinationValuePointHandle.SetValue(sourceValuePointHandle.GetValue());
            }
            private static ValuePointHandle GetValuePointHandle(object instance, string navigationPath)
            {
                var propertyName = new String(navigationPath.TakeWhile(x => x != '.').ToArray());
                var property = instance.GetType().GetProperty(propertyName);
                if (propertyName.Length != navigationPath.Length)
                {
                    var propertyInstance = property.GetValue(instance, null);
                    return GetValuePointHandle(propertyInstance, navigationPath.Substring(propertyName.Length + 1, navigationPath.Length - propertyName.Length - 1));
                }
                else
                    return new ValuePointHandle(instance, property);
            }
            class ValuePointHandle
            {
                public object Instance
                {
                    get;
                    private set;
                }
                public PropertyInfo Property
                {
                    get;
                    private set;
                }
                public ValuePointHandle(object instance, PropertyInfo property)
                {
                    Instance = instance;
                    Property = property;
                }
                public void SetValue(object value)
                {
                    Property.SetValue(Instance, value, null);
                }
                public object GetValue()
                {
                    return Property.GetValue(Instance, null);
                }
            }
        }
        class F1
        {
            public int Q
            {
                get;
                set;
            }
            public F2 F2
            {
                get;
                set;
            }
        }
        class F2
        {
            public string Name
            {
                get;
                set;
            }
        }
        class F3
        {
            public int Q
            {
                get;
                set;
            }
            public F2 F2
            {
                get;
                set;
            }
        }
    }
}