Question

我已经阅读了很多关于如何使用 ExpandoObject 通过添加属性从头开始动态创建对象的内容，但我还没有找到你如何做同样的事情开始来自您已经拥有的非动态C＃对象。

例如，我有这个琐碎的课程：

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我想将它转换为ExpandoObject，以便我可以根据它已经添加或删除属性，而不是从头开始重建相同的东西。这可能吗？

编辑：标记为重复的问题显然不会与此重复。

Answer 1

可以这样做：

var person = new Person { Id = 1, Name = "John Doe" };

var expando = new ExpandoObject();
var dictionary = (IDictionary<string, object>)expando;

foreach (var property in person.GetType().GetProperties())
    dictionary.Add(property.Name, property.GetValue(person));

Answer 2

您无法将Person类“转换”为expando对象。但是，您可以创建包含Person的包装器DynamicObject并转发所有字段。

using System;
using System.Collections.Generic;
using System.Dynamic;
using System.Reflection;

namespace SandboxConsole
{
    public class ExpandoWrapper : DynamicObject
    {
        private readonly object _item;
        private readonly Dictionary<string, PropertyInfo> _lookup = new Dictionary<string, PropertyInfo>(StringComparer.InvariantCulture);
        private readonly Dictionary<string, PropertyInfo> _ignoreCaseLookup = new Dictionary<string, PropertyInfo>(StringComparer.InvariantCultureIgnoreCase);

        private readonly Dictionary<string, Box> _lookupExtra = new Dictionary<string, Box>(StringComparer.InvariantCulture);
        private readonly Dictionary<string, Box> _ignoreCaseLookupExtra = new Dictionary<string, Box>(StringComparer.InvariantCultureIgnoreCase);

        private class Box
        {
            public Box(object item)
            {
                Item = item;
            }
            public object Item { get; }
        }

        public ExpandoWrapper(object item)
        {
            _item = item;
            var itemType = item.GetType();
            foreach (var propertyInfo in itemType.GetProperties())
            {
                _lookup.Add(propertyInfo.Name, propertyInfo);
                _ignoreCaseLookup.Add(propertyInfo.Name, propertyInfo);
            }
        }
        public override bool TryGetMember(GetMemberBinder binder, out object result)
        {
            result = null;
            PropertyInfo lookup;
            if (binder.IgnoreCase)
            {
                _ignoreCaseLookup.TryGetValue(binder.Name, out lookup);
            }
            else
            {
                _lookup.TryGetValue(binder.Name, out lookup);
            }

            if (lookup != null)
            {
                result = lookup.GetValue(_item);
                return true;
            }

            Box box;
            if (binder.IgnoreCase)
            {
                _ignoreCaseLookupExtra.TryGetValue(binder.Name, out box);
            }
            else
            {
                _lookupExtra.TryGetValue(binder.Name, out box);
            }

            if (box != null)
            {
                result = box.Item;
                return true;
            }

            return false;
        }

        public override bool TrySetMember(SetMemberBinder binder, object value)
        {
            PropertyInfo lookup;
            if (binder.IgnoreCase)
            {
                _ignoreCaseLookup.TryGetValue(binder.Name, out lookup);
            }
            else
            {
                _lookup.TryGetValue(binder.Name, out lookup);
            }

            if (lookup != null)
            {
                lookup.SetValue(_item, value);
                return true;
            }

            var box = new Box(value);
            _ignoreCaseLookupExtra[binder.Name] = box;
            _lookupExtra[binder.Name] = box;

            return true;
        }
    }
}

示例用法

using System;

namespace SandboxConsole
{
    class Program
    {
        static void Main(string[] args)
        {
            var person = new Person() {Id = 1};
            dynamic wrapper = new ExpandoWrapper(person);

            wrapper.Id = 2;
            wrapper.NewField = "Foo";

            Console.WriteLine(wrapper.Id);
            Console.WriteLine(person.Id);
            Console.WriteLine(wrapper.NewField);
        }
    }
    public class Person
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public string Address { get; set; }
        public string Telephone { get; set; }
    }
}

如何将任何C＃对象转换为ExpandoObject？

2 个答案: