How do you convert any C# object to an ExpandoObje

问题:

This question already has answers here:

Convert class to dynamic and add properties (5 answers)

can one convert a dynamic object to an ExpandoObject (c#) (2 answers)

How to extend an existing object in c# 4.0 using dynamics (1 answer)

Closed 2 years ago.

I've read a lot about how ExpandoObject can be used to dynamically create objects from scratch by adding properties, but I haven't yet found how you do the same thing starting from a non-dynamic C# object that you already have.

For instance, I have this trivial class:

public class Person
{
    public int Id { get; set; }
    public string Name { get; set; }
    public string Address { get; set; }
    public string Telephone { get; set; }
}

I would like to convert this to ExpandoObject so that I can add or remove properties based on what it has already, rather than rebuilding the same thing from scratch. Is this possible?

Edit: the questions marked as duplicate are clearly NOT duplicates of this one.

回答1:

It could be done like this:

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));

回答2:

You can not "convert" a Person class in to a expando object. However you could create a wrapper DynamicObject that contains a Person and forwards all of the fields.

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;
        }
    }
}

example usage

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; }
    }
}