javascript - Post a json object to mvc controller with jquery and ajax

Question

I am trying to submit some values from a form to my mvc controller.

Here is my controller:

 //Post/ Roles/AddUser
    [HttpPost]       
    public ActionResult AddUser(String json)
    {
        Log.submit(json);            
        return View();
    }

here is the js:

<script>
function submitForm() {

    var usersRoles = new Array;
    $("#dualSelectRoles2 option").each(function () {
        usersRoles.push($(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);
        }
    });
}

When I debug on the controller I get my parameter to be null? The console.log(usersRoles) gives me data.

What am I doing incorrectly?

How can I receive a json object in the controller?

Answer 1

I see in your code that you are trying to pass an ARRAY to POST action. In that case follow below working code -

<script src="~/Scripts/jquery-1.10.2.min.js"></script>
<script>
    function submitForm() {
        var roles = ["role1", "role2", "role3"];

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

<input type="button" value="Click" onclick="submitForm()"/>

And the controller action is going to be -

    public ActionResult AddUser(List<String> Roles)
    {
        return null;
    }

Then when you click on the button -