Question

i am trying to post my model to the server through an ajax call. Unfortunately the Model is not updated?

 <script src="../../Scripts/jquery-1.4.1.min.js" type="text/javascript"></script>

<form id="ajaxForm" action="">
    <div>
        name:<%= Html.TextBoxFor(model => model.number) %>
    </div>
    <%--hidden vars--%>
    <input type="hidden" id="Hidden1" />
    <%= Html.Hidden("myModel", Model.Serialize())%>
</form>
<button id="submitbutton">
    save
</button>

<script type="text/javascript">

    $(document).ready(function () {
        $("#submitbutton").click(function () {
            var FormData = $("#ajaxForm").serialize();
            $.ajax({
                type: 'POST',
                url: "/Home/SaveAjax",
                data: { inputdata: $("#myModel").val() },
                datatype: 'JSON'
            });
        })
    });

</script>




    [HttpPost]
    public JsonResult SaveAjax(string inputdata)
    {
        MyModel myModel = (inputdata.DeSerialize() ?? TempData["myModel"] ?? new MyModel()) as MyModel;

        //TryUpdateModel does not update my model??
        TryUpdateModel(myModel);

        TempData["myModel"] = myModel;

        return Json(new { resultaat = "finished" });
    }


 [Serializable]
public class MyModel
{
    //[Required]
    public string name { get; set; }
    public bool flag { get; set; }
    public int number { get; set; }
    public string address { get; set; }
    public string abn { get; set; }
    public string postalcode { get; set; }
}


public static class Extensions
{
    public static string Serialize(this object myobject)
    {
        var sw = new StringWriter();
        var formatter = new LosFormatter();
        formatter.Serialize(sw, myobject);
        return sw.ToString();
    }

    public static object DeSerialize(this string mystring)
    {
        if (string.IsNullOrEmpty(mystring))
            return null;
        var formatter = new LosFormatter();
        MyModel mym = (MyModel)formatter.Deserialize(mystring);
        return mym;
    }
}

Answer 1

In your AJAX request you are sending only the value of the hidden field:

data: { inputdata: $("#myModel").val() }

so you cannot expect to get any other values on your server than this hidden field. If you want to POST the entire form contents use the formData variable that you declared in your code but left unused:

$('#submitbutton').click(function () {
    var formData = $('#ajaxForm').serialize();
    $.ajax({
        type: 'POST',
        url: '/Home/SaveAjax',
        data: formData,
        dataType: 'json'
    });
});