Question

I have a scrollable GridView in my Web Part and I have to make an AJAX call on each user scroll. I use Jquery 1.7.1 in the web part to call a c# handler class.

I am getting error 500 : Internal Server Error.

Here is a sample of the ascx :

<div id="divProducts" style="height:300px;overflow:auto">
    <asp:GridView ID="GridView1" runat="server" CellPadding="4" ForeColor="#333333" EnableViewState="false">
        <AlternatingRowStyle BackColor="White" />
        <FooterStyle BackColor="#990000" Font-Bold="True" ForeColor="White" />
        <HeaderStyle CssClass="header" BackColor="#990000" Font-Bold="True" ForeColor="White" />
        <PagerStyle BackColor="#FFCC66" ForeColor="#333333" HorizontalAlign="Center" />
        <RowStyle BackColor="#FFFBD6" ForeColor="#333333" />
    </asp:GridView>
</div>

<div id="divProgress" style="margin-top: -50px;margin-left:150px;z-index:-999">
    <asp:Image ID="image1" ImageUrl="~/_layouts/images/MyWebPart/loading.gif" width="100" height="100" runat="server" />
</div>

<script type="text/javascript">
    $(document).ready(function () {

        //initially hide the loading gif
        $("#divProgress").hide();

        //Attach function to the scroll event of the div
        $("#divProducts").scroll(function () {

            //User has scrolled to the end of the grid. Load new data..
            $("#divProgress").ajaxStart(function () {
                $(this).show();
            });
            $("#divProgress").ajaxStop(function () {
                $(this).hide();
            });

            BindNewData();

        });

    });

    function BindNewData() {
            $.ajax({
                type: "GET",
                url: "/_layouts/MyWebPart/FetchRecordsHandler.ashx",
                success: function (data) {
                    alert('data ', data);
                },
                error: function (xhr, ajaxOptions, thrownError) {
                    alert(xhr.status);
                    alert(thrownError);
                }  
            });
        }
</script>

I added a ASHX file that will be deployed in Layouts folder of my web part project (Layouts/MyWebPart/FetchRecordsHandler.ashx) :

<%@ WebHandler Language="C#" Class="MyWebPart.Code.FetchRecordsHandler" CodeBehind="FetchRecordsHandler.cs" %>

And I created the class FetchRecordsHandler that implements IHttpHandler with correct namespace :

namespace MyWebPart.Code
{
    class FetchRecordsHandler : IHttpHandler
    {
        public void ProcessRequest(HttpContext context)
        {

            context.Response.Write("From the handler at " + DateTime.Now);

        }

        public bool IsReusable
        {
            get
            {
                return false;
            }
        }
    }
}

This method doesn’t work in my web part. Any idea of a solution or maybe another technic to make ajax calls from the scroll events to the web part ?

Thx

Answer 1

You need to change your .ashx to something like:

<%@ WebHandler Language="C#" Class="MyWebPart.Code.FetchRecordsHandler, {my assembly}, Version=1.0.0.0, Culture=neutral, PublicKeyToken=xxxxxxxxxxxxxxxx" %>

Where {my assembly} is the name of the compiled .dll (without the .dll), probably MyWebPart and xxxxxxxxxxxxxxxx is the public key token for your assembly. One way to find this would be to look at the deployed .ascx from your web part, the first line or so should contain something similar.

I imagine the 500 error you are receiving has something to do with the fact that SharePoint cannot load the assembly for your .ashx. You could look in the event viewer for more details.