Simple Reflection Based Assignment Using Extension Methods

Have you ever had two objects, of different types, and wished that C# could just be smart enough to realize that objA.FirstName should be assigned to objB.FirstName?  For me this comes up quite a bit when working with WCF services.  I don’t want a service to directly expose my internal business object type, because that type might change on a different schedule than that of my data contract.  So I often end up with objects that have identical property names, usually the service being a subset of the internal class, but obviously of different types.  How can I handle assigning objDC from objInternal without writing a line of code (or generating a line of code) for every single property?  Enter AssignFrom … with this code, you’ll get something as simple as objDC.AssignFrom(objInternal);

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Reflection;
using System.Diagnostics;

namespace TestCSharp
{
    public static class ObjectExtensions
    {
        public static T AssignFrom<T>(this T obj, object from)
        {
            Type toType = obj.GetType();
            Type fromType = from.GetType();

            var toInfo = toType.GetProperties();
            var fromInfo = fromType.GetProperties();

            foreach (var fromProp in fromInfo)
            {
                bool assigned = false;
                foreach (var toProp in toInfo)
                {

                    if (toProp.CanWrite && fromProp.CanRead &&
                        toProp.PropertyType.Equals(fromProp.PropertyType) &&
                        toProp.Name.Equals(fromProp.Name) &&
                        toProp.GetIndexParameters().Count() == 0 &&
                        fromProp.GetIndexParameters().Count() == 0)
                    {
                        toProp.SetValue(obj, fromProp.GetValue(from, null), null);
                        assigned = true;
                    }
                }

                Debug.Assert(assigned, 
                    string.Format(
                    "Property {0} was not populated to the To object.", 
                    fromProp.Name));
            }

            return obj;
        }
    }
}

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