JavaScriptSerializer with custom Type - asp.net

Question

I have a function with a List return type. I'm using this in a JSON-enabled WebService like:
[WebMethod(EnableSession = true)]
[ScriptMethod(ResponseFormat = ResponseFormat.Json)]
public List<Product> GetProducts(string dummy) /* without a parameter, it will not go through */
{
return new x.GetProducts();
}
this returns:
{"d":[{"__type":"Product","Id":"2316","Name":"Big Something ","Price":"3000","Quantity":"5"}]}
I need to use this code in a simple aspx file too, so I created a JavaScriptSerializer:
JavaScriptSerializer js = new JavaScriptSerializer();
StringBuilder sb = new StringBuilder();
List<Product> products = base.GetProducts();
js.RegisterConverters(new JavaScriptConverter[] { new ProductConverter() });
js.Serialize(products, sb);
string _jsonShopbasket = sb.ToString();
but it returns without a type:
[{"Id":"2316","Name":"Big One ","Price":"3000","Quantity":"5"}]
Does anyone have any clue how to get the second Serialization work like the first?
Thanks!

Answer 1

When you create the JavaScriptSerializer, pass it an instance of SimpleTypeResolver.
new JavaScriptSerializer(new SimpleTypeResolver())
No need to create your own JavaScriptConverter.

Answer 2

Ok, I have the solution, I've manually added the __type to the collection in the JavaScriptConverter class.
public class ProductConverter : JavaScriptConverter
{ public override IDictionary<string, object> Serialize(object obj, JavaScriptSerializer serializer)
{
Product p = obj as Product;
if (p == null)
{
throw new InvalidOperationException("object must be of the Product type");
}
IDictionary<string, object> json = new Dictionary<string, object>();
json.Add("__type", "Product");
json.Add("Id", p.Id);
json.Add("Name", p.Name);
json.Add("Price", p.Price);
return json;
}
}
Is there any "offical" way to do this?:)

Answer 3

Building on Joshua's answer, you need to implement a SimpleTypeResolver
Here is the "official" way that worked for me.
1) Create this class
using System;
using System.Web;
using System.Web.Compilation;
using System.Web.Script.Serialization;
namespace XYZ.Util
{
/// <summary>
/// as __type is missing ,we need to add this
/// </summary>
public class ManualResolver : SimpleTypeResolver
{
public ManualResolver() { }
public override Type ResolveType(string id)
{
return System.Web.Compilation.BuildManager.GetType(id, false);
}
}
}
2) Use it to serialize
var s = new System.Web.Script.Serialization.JavaScriptSerializer(new XYZ.Util.ManualResolver());
string resultJs = s.Serialize(result);
lblJs.Text = string.Format("<script>var resultObj = {0};</script>", resultJs);
3) Use it to deserialize
System.Web.Script.Serialization.JavaScriptSerializer(new XYZ.Util.ManualResolver());
var result = json.Deserialize<ShoppingCartItem[]>(jsonItemArray);
Full post here: http://www.agilechai.com/content/serialize-and-deserialize-to-json-from-asp-net/