Download excel file using Ajax MVC - asp.net-mvc-5

Question

How to download a file using Ajax in MVC. If no data to generate file then show error label.
I'm trying using action result method which returns File. I can download file . but don't want to refresh the page if no file to download.
My code is like 
public ActionResult Excel(MyViewModel model)
{
var result = // DB call to get data
if (no data)
{
return **something**
}
else
{
  byte[] excelContent =//passing result to my method( returns xls file in byte)
    return File(
                    excelContent, "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet",
                    reportName + " Report " + startDate + " - " + endDate + ".xlsx");
}
}
What should I return for something
For now I'm returning emptyResult for something hence I got blank page if no data.
Ajax doesn't support file download.
This code works if I submit the form and there is data.
Suggest something in which page will not get refresh and both task get achieved.
1. File download if data
2. Show error label if no data

Answer 1

If get file using Ajax then best way to create API
Function return type is FileResult
var exportToExcel = function (inputData, fileName) {
var path = "url";
var form = $("<form></form>");
form.attr("enctype", "application/x-www-form-urlencoded");
form.attr("method", "post");
form.attr("action", path);
form.attr("accept-charset", "UTF-8");
var field = $("<input></input>");
field.attr("type", "hidden");
field.attr("name", "data");
field.attr("value", escape(JSON.stringify(inputData)));
form.append(field);
var field2 = $("<input></input>");
field2.attr("name", "fileName");
field2.attr("value", fileName);
form.append(field2);
$(document.body).append(form);
form.submit().remove();
};
var downloadFile = function (inputData) {
// checkFileHasResult is ajax call result if true or false
checkFileHasResult(inputData).then(function (hasFile) {
if (hasFile === true) {
// give file name with extension
exportToExcel(inputData, "asdfasdf.csv");
}
});
};

Answer 2

Doing a quick search in Google, brought up quite a few results, as this question.
In JQuery, you could just point you 'window.location' to your action method in the controller, that returns a FileResult. This will download the file for you.
I would suggest, you return message to an ajax call, stating whether your download was successful or not, and then you can set some sort of text on the front end to notify the user that this process was unsuccessful.
Here is how I would have accomplished this. You can tweak it to work for you. Here is an example of the controller methods.
[HttpGet]
public JsonResult ExportCollection()
{
//Build your excel file, and save it to disk somewhere on server.
//you can also save it in session, depending on size
//Build up response Messages based on success or not
//return json object with your file path
return Json(new { responseMessage = responseMessage }, JsonRequestBehavior.AllowGet);
}
public ActionResult Download(string fileName)
{
return File(model.FilePath, "application/vnd.ms-excel", fileName);
}
And then, call these actions from client side using JQuery and an Ajax call.
$(document).on("click", "#YourButton", function () {
var url = "/YourController/ExportCollection/"
$("#responseText").text("We're getting things ready. Please wait...");
$('#loadingImage').show();
$.ajax({
url: url,
type: "get",
success: function (responseMessage) {
patientCollectionExportSuccess(responseMessage);
}
});
})
//Function responsible for exporting
function patientCollectionExportSuccess(dataReceived) {
var respMessage = dataReceived.responseMessage;
if (respMessage != null) {
if (respMessage != "Error: Not Exported.") {
$("#responseText").text("Download completed.");
$('#loadingImage').hide();
//set window.location to redirect to FileResult, which will download file
window.location = '/PatientListingQuery/Download?fileName=' + respMessage ;
}
else {
$("#responseText").text("Download unsuccessful.");
$('#loadingImage').hide();
$("#responseText").text(dataReceived.responseMessage);
}
}
}

Answer 3

Thanks guys
I got solution
It works for me smoothly ....
my form action is pointing to another method, so updated action before submitting the form. and after file download, i'm setting it to old form action.
$(document).ready(function () {
$('#excel-button').on('click', function () {
$.ajax({
url: '/MyController/IsData',
type: 'POST',
data: $("#myForm").serialize(),
success: function (response) {
if (response == "True") {
var oldUrl="";
var form1 = $('#myForm');
var frm = document.getElementById('myForm') || null;
if (frm) {
oldUrl = frm.action;
frm.action = '/MyController/GenerateExcel';
}
form1.submit();
frm.action = oldUrl;
$('.error-Message').hide();
} else {
$('.error-Message').show();
}
}
});
});