Question

我需要动态设置属性值

我读了这个Get property value from string using reflection in C#

并使用以下代码获取值

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

但这不是设定。我如何制作一个通用的setter方法来简化这项工作？

Answer 1

这一行不正确：

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

您正尝试将emp2.Address.City设置为在给定对象上调用属性的setter的结果。

在这种情况下，你为什么要使用反射？根据您的代码行，您只需编写

即可

emp2.Address.City = city;

因为您的反射代码也设置了emp2的属性。因此即使它起作用，它也会做两次相同的事情。

您的代码就像写作一样：

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;
            }
        }
    }

}

设置属性值

2 个答案: