ASP.NET MVC - access parameters NOT posted via form - asp.net-mvc

Question

Current Scenario
I am using MVC 4, .net 4.5 on vs2012. I have an action which accepts a custom type. This custom type(model) is tightly bound to a view. I am making a POST via AJAX using JSON. Post will only post the relevant data and no form. Its content type is "application/json; charset=UTF-8". I am getting a nicely populated(read valid) model in my action.
The issue
Now I need to add a custom filter but I am unable to access the data via Request, Request.Form, Request.Param? I have been looking in System.Web.HttpContext.Current. If data is getting populated in my model, then it has to be somewhere in the request itself. I guess I am missing the finer print.
The javascript for posting data is somewhat like
$("#postData").click(function (event) {
var savedObject = getJson(savedObject, parentContext);
$.ajax({
url: '/controller/action',
contentType: 'application/json',
dataType: 'json',
data: savedObject,
type: "POST",
success: successCallBack,
error: errorCallBack
});
});

Answer 1

I see your stated wish of sending JSON data only. If you really need to stick to this, you can access the raw parameters via Request.InputStream.
Controller:
var input = new StreamReader(Request.InputStream).ReadToEnd();
This will get you a URL encoded string that you can manually parse.
Really, I would recommend Shahrooz's answer as the correct way to get where you want to go.
If the controller's Request.Form is not populating for your Ajax post, it is likely because you are manually serializing and sending the data to the controller with a contentType of application/json (a common scenario).
Here is an jQuery.ajax example that will NOT populate Request.Form on the controller.
// JSON serialized form data.
var data = {"id" : "1234", "name" : "Dave"};
$.ajax({
type: "POST",
url: serviceUrl,
contentType: "application/json",
dataType: "json",
data: JSON.stringify(data || {}),
success: function () { }
});
Changing the contentType will cause the controller to process the post like a form submission.
// Form encoded data.
var data = {"id" : "1234", "name" : "Dave"};
data = $.param(data);
$.ajax({
type: "POST",
url: serviceUrl,
contentType: "application/x-www-form-urlencoded; charset=UTF-8",
dataType: "json",
data: data,
success: function () { }
});
You can also leave contentType undefined as application/x-www-form-urlencoded; charset=UTF-8 it is the jQuery default.
I would note that I only used $.ajax to better illustrate what is going on. You could also use $.post, though you will still need to send form encoded data

Answer 2

I dont know what is your code but .If you remove contentType: "application/json; charset=utf-8" from your call to jQuery.ajax the default content type (form-urlencoded) will be used and the json data you have specified as your data parameter (data: { i: i, s: s, b: b }) will be mapped correctly to your action parameters....so unless you really want to send json data just remove the contentType and you will be fine.....look at this