Question

I am trying to make an ajax sending data in JSON from a partial view. I get a System.ArgumentException: Invalid JSON primitive: undefined.
When I evaluate the object in a browser data contains an int and two strings. Can anyone tell me what I am doing wrong?

Partial View

@model FTD.Models.FTDAccountExtended
@using (Html.BeginForm()) {
<fieldset>
<legend>Update Policy Number</legend>
@Html.HiddenFor(m => m.account.ftd_accountsid)
@Html.HiddenFor(m => m.OldPolicyNumber)
@Html.TextBoxFor(m => m.account.ftd_policyno)
<input type="button" value="update" id="update" />
</fieldset>
}

<script type="text/javascript">
 $(document).ready(function () {
     $("#update").click(function () {
         var myUrl = '@Url.Content("~/")' + '/Maintenance/UpdatePolicyNumber';
         var data = [{ 'ClientNumber': parseInt($("#account_ftd_accountsid").val()), 'OldPolicyNumber': $("#OldPolicyNumber").val(), 'NewPolicyNumber': $("#account_ftd_policyno").val()}];
         $.ajax({
             url: myUrl,
             type: 'POST',
             data: data,
             contentType: 'application/json; charset=utf-8',
             success: function (data) {
                 alert(data.message);
             },
             error: function (errMsg) {
                 alert("Error", errMsg);
             }
         });
     });
 });

The controller method is

public ActionResult UpdatePolicyNumber(int ClientNumber, string OldPolicyNumber, string NewPolicyNumber)
{
    var message = string.Format("UpdatePolicyNumber CN:{0} OP:{1} NP:{2}", ClientNumber, OldPolicyNumber, NewPolicyNumber);
    if (_log.IsDebugEnabled)
        _log.Debug(message);
    if (!string.IsNullOrEmpty(NewPolicyNumber) && ClientNumber > 0)
    {
        _entities = new CloseFTD_Entities();
        _entities.UpdatePolicyNumber(ClientNumber, OldPolicyNumber, NewPolicyNumber, User.Identity.Name);

     }
     return Json
        (
           new
           {
               message = message
           },
           JsonRequestBehavior.AllowGet
         );
}

Answer 1

I would just try posting the the data as a java script object (as Marc mentioned above)
and remove the content type attribute.