JavaScriptSerializer with custom Type

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?



Thank you for visiting the Q&A section on Magenaut. Please note that all the answers may not help you solve the issue immediately. So please treat them as advisements. If you found the post helpful (or not), leave a comment & I’ll get back to you as soon as possible.

Method 1

When you create the JavaScriptSerializer, pass it an instance of SimpleTypeResolver.

new JavaScriptSerializer(new SimpleTypeResolver())

No need to create your own JavaScriptConverter.

Method 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?:)

Method 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:

All methods was sourced from or, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0

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