[asp.net] How to receive JSON as an MVC 5 action method parameter

I have been trying the whole afternoon crawling through the web trying to receive a JSON object in the action controller.

What is the correct and or easier way to go about doing it?

I have tried the following: 1:

//Post/ Roles/AddUser
[HttpPost]
public ActionResult AddUser(String model)
{
    if(model != null)
    {
        return Json("Success");
    }else
    {
        return Json("An Error Has occoured");
    }

}

Which gave me a null value on my input.

2:

//Post/ Roles/AddUser
[HttpPost]
public ActionResult AddUser(IDictionary<string, object> model)
{
    if(model != null)
    {
        return Json("Success");
    }else
    {
        return Json("An Error Has occoured");
    }

}

which gives me a 500 error on the jquery side which is trying to post to it? (meaning that it didn't bind correctly).

here is my jQuery code:

<script>
function submitForm() {

    var usersRoles = new Array;
    jQuery("#dualSelectRoles2 option").each(function () {
        usersRoles.push(jQuery(this).val());
    });
    console.log(usersRoles);

    jQuery.ajax({
        type: "POST",
        url: "@Url.Action("AddUser")",
        contentType: "application/json; charset=utf-8",
        dataType: "json",
        data: JSON.stringify(usersRoles),
        success: function (data) { alert(data); },
        failure: function (errMsg) {
            alert(errMsg);
        }
    });
}

All I want to do is receive my JSON object in my mvc action?

You are sending a array of string

var usersRoles = [];
jQuery("#dualSelectRoles2 option").each(function () {
    usersRoles.push(jQuery(this).val());
});   

So change model type accordingly

 public ActionResult AddUser(List<string> model)
 {
 }

fwiw, this didn't work for me until I had this in the ajax call:

contentType: "application/json; charset=utf-8",

using Asp.Net MVC 4.

There are a couple issues here. First, you need to make sure to bind your JSON object back to the model in the controller. This is done by changing

data: JSON.stringify(usersRoles),

to

data: { model: JSON.stringify(usersRoles) },

Secondly, you aren't binding types correctly with your jquery call. If you remove

contentType: "application/json; charset=utf-8",

it will inherently bind back to a string.

All together, use the first ActionResult method and the following jquery ajax call:

    jQuery.ajax({
        type: "POST",
        url: "@Url.Action("AddUser")",
        dataType: "json",
        data: { model: JSON.stringify(usersRoles) },
        success: function (data) { alert(data); },
        failure: function (errMsg) {
        alert(errMsg);
        }
   });