Asp.Net MVC 3 JSON Model Binding not working

Question

I am using MVC3 and that i know MVC3 support binding JSON literal to Action parameter. But i can't do it successfully;

I have a class name Tag

public class Tag
{
    public int tagId { get; set; }
    public string tagName { get; set; }
}

An Action on controller called Tag

    [HttpPost]
    public ActionResult Tag(Tag tag)
    {
        // Here will be codes...
        return Json(new { success = 0 });
    }

Javascript code that send js object as JSON to my action

    var tag ={tagId:5,tagName:"hello"};
    $.ajax({
           url: "/image/tag",
           type: "POST",
           data: $.toJSON(tag),
           success: function (r) {
               if (r.success == 1) {
                   window.location = r.redirect;
               }
           }

Post Data that I see in Firebug Net tab

{"tagId":5,"tagName":"hello"}

Parameter name tag in Tag Action is not null but has values O for tagId and null for tagName. What the problem in here?

Answer 1

You need to set the content type of the request to application/json:

$.ajax({
    url: '/image/tag',
    type: 'POST',
    contentType: 'application/json; charset=utf-8',
    data: $.toJSON(tag),
    success: function (r) {
        if (r.success == 1) {
            window.location.href = r.redirect;
        }
    }
});

Ah, and you don't need to have your Tag model properties start with a lowercase letter:

public class Tag
{
    public int TagId { get; set; }
    public string TagName { get; set; }
}

Remark 1: The JavaScriptSerializer class that ASP.NET MVC 3 uses behind the scenes is capable of properly handling this.

Remark 2: In your Tag action you seem to be returning the following JSON: {"success":0} whereas in your success AJAX callback you seem to be using some r.redirect property which doesn't exist.

Remark 3: Avoid naming your controller actions the same way as your view models. Normally action names should represent verbs (like List, Save, Delete, ...) whereas view models represent resources (TagModel, ...).