A RestSharp XML deserializer that can deserialize derived classes.

BaseXmlDeserializer.md

Assume you have these classes:

public class Base
{
}

public class Derived : Base
{
}

The RestSharp.Deserializers.DotNetXmlDeserializer (which uses System.Xml.Serialization.XmlSerializer) fails when trying to deserialize the following to Base:

<?xml version="1.0" encoding="utf-8"?>
<Derived />

This deserializer checks the root element's name to determine the type to deserialize to using reflection.

BaseXmlDeserializer.cs

using RestSharp;
using RestSharp.Deserializers;
using RestSharp.Serializers;
using System;
using System.IO;
using System.Linq;
using System.Reflection;
using System.Text;
using System.Xml.Linq;
using System.Xml.Serialization;

namespace RestSharpXmlDeserializer
{
    /// <summary>
    /// This deserializer checks the root element's name to determine the type to deserialize to using reflection.
    /// </summary>
    public class BaseXmlDeserializer : IDeserializer
    {
        public string DateFormat { get; set; }

        public string Namespace { get; set; }

        public string RootElement { get; set; }

        public T Deserialize<T>(IRestResponse response)
        {
            if (string.IsNullOrEmpty(response.Content))
            {
                return default(T);
            }

            var root = XElement.Parse(response.Content).Name.LocalName;
            var type = typeof(T);
            if (!string.Equals(type.Name, root, StringComparison.OrdinalIgnoreCase))
            {
                type = Assembly.GetAssembly(type).GetTypes()
                    .First(t => t != type && type.IsAssignableFrom(t) && string.Equals(t.Name, root, StringComparison.OrdinalIgnoreCase));
            }

            using (var stream = new MemoryStream(Encoding.UTF8.GetBytes(response.Content)))
            {
                var serializer = new System.Xml.Serialization.XmlSerializer(type);
                return (T)serializer.Deserialize(stream);
            }
        }
    }
}