loosing hidden field value after ajax call to c# code

Question

Using jquery 1.7.2 and .net 4.0

I have a json ajax call that sets the value of a asp hidden field on my form. While stepping through the code behind I can see the value the hidden field is set but when the code returns to the aspx code the value is empty. ASPX code:

    <asp:HiddenField ID="hidden1" runat="server" />
    //dropdownlist on change event calls the function below:
     function getReport() {
            var data = { MethodName: 'myMethod', value1: value1 }
            var options = {
                url: '<%=ResolveUrl("myPage.aspx") %>',
                async: false,
                data: data,
                datatype: 'text',
                type: 'POST',
                success: function () {
                    var returnedData = $("#hidden1").val();
                    alert('returned data = ' + returnedData);
                }
            }
            $.ajax(options);
//also tried alerting the returned data here.. still empty
        }

c# code behind:

#region AJAX
        if (Request.Form["MethodName"] == "myMethod")
        {

            hidden1.Value = "please just pass this value!!!";
            return;
        }
        else
        {
            //do something different.
        }
        #endregion

I've simplified my code, hopefully not too much. and I double checked my code to make sure the hidden field value is not set elsewhere in the code.

Answer 1

Due to the ajax call the the hidden field will not be updated. You must use the data which is returned by the ajax call.

 function getReport() {
        var data = { MethodName: 'myMethod', value1: value1 }
        var options = {
            url: '<%=ResolveUrl("myPage.aspx") %>',
            async: false,
            data: data,
            datatype: 'text',
            type: 'POST',
            success: function (returnedData) {
                alert('returned data = ' + returnedData);
            }
        }
        $.ajax(options);
    }

code behind:

#region AJAX
if (Request.Form["MethodName"] == "myMethod")
{
     return "please just pass this value!!!";
}
else
{
     //do something different.
}

#endregion