ASP.NET Web Api RC: JSON deserialization into object properties

Question

I am having an issue with JSON deserialization of string values into C# properties of type object, they end up as an array of strings.

The value of foo.Bar in the Get and Post method is string[1]{"test"}, but I am expecting string "test".

I have tried attributing Foo with DataContract / DataMember, and JsonObject / JsonProperty attributes and get the same result.

Any idea why this is happening?

Here is my code from a empty Asp.net MVC3 Project. I installed the Microsoft.AspNet.WebApi RC nuget package version 4.0.20505.0 and jquery v 1.7.2

Update Updated code to include Get action and contentType: "application/json"

Global.asax

using System;
using System.Collections.Generic;
public class MvcApplication : System.Web.HttpApplication
{
    public static void RegisterGlobalFilters(GlobalFilterCollection filters)
    {
        filters.Add(new HandleErrorAttribute());
    }

    public static void RegisterRoutes(RouteCollection routes)
    {
        routes.IgnoreRoute("{resource}.axd/{*pathInfo}");

        routes.MapHttpRoute(
            name: "WebApi",
            routeTemplate: "api/{controller}"
        );

        routes.MapRoute(
            "Default", // Route name
            "{controller}/{action}/{id}", // URL with parameters
            new { controller = "Home", action = "Index", 
                                       id = UrlParameter.Optional }
        );
    }

    protected void Application_Start()
    {
        AreaRegistration.RegisterAllAreas();

        RegisterGlobalFilters(GlobalFilters.Filters);
        RegisterRoutes(RouteTable.Routes);            
    }
}

My Test Controller

using System.Linq;
using System.Web;
using System.Web.Mvc;

namespace WebApiRCTest.Controllers
{
    public class TestController : System.Web.Http.ApiController
    {
        public IEnumerable<string> Get([System.Web.Http.FromUri]Foo foo)
        {
            return new List<string>();
        }
        public void Post([System.Web.Http.FromBody]Foo foo)
        {
            object bar = foo.Bar;
        }
    }
    public class Foo
    {
        public object Bar { get; set; }
    }
}

My JavaScript

function post() {
    $.ajax({
        url: "http://localhost:55700/api/ApiTest/",
        type: "GET",
        dataType: "json",
        accept: "application/json",
        contentType: "application/json",
        data: { Bar: "test" }
    })
    $.ajax({
        url: "http://localhost:55700/api/Test/",
        type: "POST",
        dataType: "json",
        accept: "application/json",
        contentType: "application/json",
        data: { Bar: "test" }
    })
}

Mike Wasson · Accepted Answer · 2012-06-15 22:52:26Z

3

This is actually sending 'application/x-www-form-urlencoded', not JSON. Try:

    $.ajax({
    url: "http://localhost:55700/api/Test/",
    type: "POST",
    dataType: 'json',
    contentType: 'application/json',
    accept: "application/json",
    data: JSON.stringify({ Bar: "test" })

answered Jun 15, 2012 at 22:52

Mike Wasson

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3 Comments

Dan Green Over a year ago

Adding the content type causes the Foo to be null in the Post Action and has no effect on the Get Action, which also gets a string array into foo.Bar

Mike Wasson Over a year ago

For JSON, you need to call JSON.stringify(). Otherwise jQuery will serialize it to form-urlencoded ("Bar=test")

Mike Wasson Over a year ago

Web API uses different formatters for JSON and form-urlencoded (application/x-www-form-urlencoded). I'm not sure why the form-urlencoded case deserializes the Bar property into an array. The JSON formatter can handle anonymous types. Also, for a GET request, the data is encoded into the URI query string, so it's not JSON, and having a content type doesn't make sense in that case. The URI will be "/api/Test/?Bar=test".

Drew Miller · Accepted Answer · 2013-05-28 14:48:13Z

0

I ran into this problem too - I created a simple attribute called JsonFromUri that does basically what it says. You can get it from nuget or check it out yourself here:

https://github.com/itsdrewmiller/JsonFromUri

answered May 28, 2013 at 14:48

Drew Miller

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