In C#, how do you one-way serialize the unserializable?

How about an extension method with your own logic (and maybe some Reflection)?

public static class SerializerExtension
{
    public static String OneWaySerialize(this Object obj)
    {
        if (Object.ReferenceEquals(obj, null))
        {
            return "NULL";
        }
        if (obj.GetType().IsPrimitive || obj.GetType() == typeof(String))
        {
            if (obj is String)
                return String.Format("\"{0}\"", obj);
            if (obj is Char)
                return String.Format("'{0}'", obj);
            return obj.ToString();
        }

        StringBuilder builder = new StringBuilder();
        Type objType = obj.GetType();
        if (IsEnumerableType(objType))
        {
            builder.Append("[");

            IEnumerator enumerator = ((IEnumerable)obj).GetEnumerator();
            Boolean moreElements = enumerator.MoveNext();
            while (moreElements)
            {
                builder.Append(enumerator.Current.OneWaySerialize());
                moreElements = enumerator.MoveNext();
                if (moreElements)
                {
                    builder.Append(",");
                }
            }

            builder.Append("]");
        }
        else
        {
            builder.AppendFormat("{0} {{ ", IsAnonymousType(objType) ? "new" : objType.Name);

            PropertyInfo[] properties = objType.GetProperties();
            for (Int32 p = properties.Length; p > 0; p--)
            {
                PropertyInfo prop = properties[p-1];
                String propName = prop.Name;
                Object propValue = prop.GetValue(obj, null);
                builder.AppendFormat("{0} = {1}", propName, propValue.OneWaySerialize());
                if (p > 1)
                {
                    builder.Append(", ");
                }
            }

            builder.Append(" }");
        }

        return builder.ToString();
    }

    // http://stackoverflow.com/a/2483054/298053
    private static Boolean IsAnonymousType(Type type)
    {
        if (type == null)
        {
            return false;
        }
        return Attribute.IsDefined(type, typeof(System.Runtime.CompilerServices.CompilerGeneratedAttribute), false)
            && type.IsGenericType && type.Name.Contains("AnonymousType")
            && (type.Name.StartsWith("<>") || type.Name.StartsWith("VB$"))
            && (type.Attributes & TypeAttributes.NotPublic) == TypeAttributes.NotPublic;
    }

    private static Boolean IsEnumerableType(Type type)
    {
        if (type == null)
        {
            return false;
        }
        foreach (Type intType in type.GetInterfaces())
        {
            if (intType.GetInterface("IEnumerable") != null || (intType.IsGenericType && intType.GetGenericTypeDefinition() == typeof(IEnumerable<>)))
            {
                return true;
            }
        }
        return false;
    }
}

Call it like so:

someDefinedObject.OneWaySerialize();

Revisisons

1. Initial version
2. Updated 12.26.2012
   • Added check for IEnumerable (thanks aboveyou00)
   • Added check for anonymous type (and just label it “new” when output)