JSON.NET serialization if override ToString

Question

I have a set of complex business objects that I'd like to serialize to Json for use in a web service. I'm currently using the DataContractJsonSerializer to product the Json, but it balks on deserialization because the default XmlReader can't handle Base64 strings.

After reading many positive reviews of Json.Net, I decided to give it a try. Surprisingly, the simplest case produces erroneous output if the business object overrides the ToString() method. Instead of generating JSON, it simply emits the string value.

For example, the following statement produces only a string, as the serializer appears to view the object as a simple string.

public class MyClass {
    public string Title{get;set;}
    public override ToString(){ return Title; }
    public string ToJson(){ 
        return JsonConvert.SerializeObject(this); 
    }
}

Instead of json formatted output, all I get is the title string. Do I have to mark the object in some special way to avoid this? Since the business object hierarchy includes many objects that override ToString(), I would rather avoid having to introduce special attributes, etc.

Answer 1

Is it possible that your actual class has a TypeConverterAttribute attached to it? I just ran into the exact same problem and found out that the TypeConverterAttribute was causing this. In thast case, this might help (at least it did for me).

This is very bad because you can inadvertently break your program (by simply adding a TypeConverter maybe for displaying the object in a PropertyGrid) without getting a compiler warning...

using Newtonsoft.Json;
using System;
using System.ComponentModel;

namespace ConsoleApplication5
{
    class Program
    {
        static void Main(string[] args)
        {
            var with = new WithTypeConverter() { Bla = 12, Blub = "With" };
            var without = new WithoutTypeConverter() { Bla = 12, Blub = "Without" };

            Console.WriteLine(with);
            Console.WriteLine(JsonConvert.SerializeObject(with));

            Console.WriteLine(without);
            Console.WriteLine(JsonConvert.SerializeObject(without));
            Console.ReadKey();
        }
    }

    public class baseClass
    {
        public int Bla { get; set; }
        public string Blub { get; set; }

        public override string ToString()
        {
            return String.Format("{0}: {1}", this.GetType().Name, Blub);
        }
    }

    [TypeConverter(typeof(ExpandableObjectConverter))]
    public class WithTypeConverter : baseClass
    {
    }

    public class WithoutTypeConverter : baseClass
    {
    }
}