Below is how I got this working.
The Key point was: I needed to use the ViewModel associated with the view in order for the runtime to be able to resolve the object in the request.
[I know that that there is a way to bind an object other than the default ViewModel object but ended up simply populating the necessary properties for my needs as I could not get it to work]
[HttpPost]
public ActionResult GetDataForInvoiceNumber(MyViewModel myViewModel)
{
var invoiceNumberQueryResult = _viewModelBuilder.HydrateMyViewModelGivenInvoiceDetail(myViewModel.InvoiceNumber, myViewModel.SelectedCompanyCode);
return Json(invoiceNumberQueryResult, JsonRequestBehavior.DenyGet);
}
The JQuery script used to call this action method:
var requestData = {
InvoiceNumber: $.trim(this.value),
SelectedCompanyCode: $.trim($('#SelectedCompanyCode').val())
};
$.ajax({
url: '/en/myController/GetDataForInvoiceNumber',
type: 'POST',
data: JSON.stringify(requestData),
dataType: 'json',
contentType: 'application/json; charset=utf-8',
error: function (xhr) {
alert('Error: ' + xhr.statusText);
},
success: function (result) {
CheckIfInvoiceFound(result);
},
async: true,
processData: false
});