Display loading message while Exporting a results set to Excel

Question

Hi Everyone,

I'm using ASP.NET and C# and am exporting a very large results set to Excel. While my export code is running I would like to show a "loading" animated gif so the users will know their request is processing. I've been trying to do this with multithreading, but I am not very familiar with it. Can anyone guide me in the right direction? Thanks!

Jon

Answer 1

I've run into this same problem with generating reports. A simple solution would be to run the report at night and then write it to the server. Then provide a link to the report.

Answer 2

Are you trying to do multi-threading on the server? What I'd recommend is in your client side javascript turn on a please wait message before posting to the server. Then on the client side when your done posting you turn the message off.

Without knowing more about your actual setup I can't help much further, but last time I implemented this I did something along these lines:

Assume we have a div called PrintLoadingPanel using JQUERY I set the div to display and take over the window:

    $("#printLoadingPanel")
       .css({display:"block",top:"0px",left:"0px",height:screen.availHeight});

I then will start a timer with a 1/2 second interval which will start checking if we are done printing. I'm only generating and downloading small PDF's so i needed a quicker response. If your report is really slow you might want to tweak this:

    window.setTimeout(checkIfDoneDownload,500);

Then my CheckIfDoneDownload function hits the server and checks if we finished generating the file and downloaded it. I am using JQUERY here again to call an AJAX enabled WCF service. You could substitute this with PageMethods or any other way to callback to the server.

function checkIfDoneDownload()
{

$.ajax({
  type: "POST",
  url: "../Services/Utilities.svc/IsPrintDownloadDone",
  data: "{}",
  contentType: "application/json; charset=utf-8",
  dataType: "json",
  success: function(msg) {
  if (msg.d)
  {
    $("#printLoadingPanel").css("display","none");
  }
  else  {window.setTimeout(checkIfDoneDownload,500);}
  },  
  error: function (xhr, textStatus, errorThrown) {
  if (xhr.status==12030) {checkIfDoneDownload();}
}
});
}

Now on the server side, I am generating my downloads via an HTTP Handler. Essentially the first thing it does is set a session level flag to false, then the last thing it does is set it back to true. My check if done service just returns the value of the flag.

Answer 3

If you're in a position to use ASP.NET AJAX then I'd recommend using the UpdateProgress control (along with an UpdatePanel).

If you're after a nice animated gif image then check out Ajaxload.