Currently, I am working on a .Net 6 Razor pages application where I have successfully implemented the functionality to download an Excel file on a button click via Ajax. The approach involves creating a new Excel workbook in memory stream using OpenXML.
C# Code
public IActionResult OnPostAjaxExport(string somedata)
{
// Creating a dummy data table
DataSet ds = MakeDummyDataSet();
// Exporting Excel via Memory Stream
MemoryStream ms = ExportDataSetViaMemoryStream(ds);
return new FileStreamResult(ms, "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet");
}
private MemoryStream ExportDataSetViaMemoryStream(DataSet ds)
{
MemoryStream memoryStream = new MemoryStream();
using (var workbook = SpreadsheetDocument.Create(memoryStream, SpreadsheetDocumentType.Workbook))
{
var workbookPart = workbook.AddWorkbookPart();
workbook.WorkbookPart.Workbook = new Workbook();
// Additional code to populate the workbook...
memoryStream.Seek(0, SeekOrigin.Begin);
return memoryStream;
}
}
Ajax code
$.ajax({
type: "POST",
url: "/Index?handler=AjaxExport",
data: payload,
xhrFields: {
responseType: 'blob'
},
headers: {
RequestVerificationToken:
$('input:hidden[name="__RequestVerificationToken"]').val()
},
success: function (result) {
var a = document.createElement('a');
var url = window.URL.createObjectURL(result);
a.href = url;
a.download = 'download.xlsx';
a.click();
window.URL.revokeObjectURL(url);
},
error: function (result) {
alert("error: " + JSON.stringify(result));
}
});
Everything is functioning as expected with this setup. However, a new requirement has surfaced which involves downloading pre-existing Excel files saved in a physical location on the server.
The challenge here is that the path to these files is not directly accessible in the browser. To tackle this, I attempted to read the files into memory stream and return them to the Ajax function following the same method used earlier.
Here is what I tried:
public IActionResult OnPostDownloadPreGeneratedFile()
{
string FilePath = @"C:\Manas\FilePath\DownloadTest\payload2.xlsx";
string ContentType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet";
// Read the file and prepare memory stream
MemoryStream ms = new MemoryStream();
FileStream file = new FileStream(FilePath, FileMode.Open, FileAccess.Read);
ms.Seek(0, SeekOrigin.Begin);
file.CopyTo(ms);
return new FileStreamResult(ms, ContentType);
}
Unfortunately, this approach does not seem to work, despite creating the same type of memory stream as before.
No errors are displayed in the console or Ajax call. After the C# code returns the FilestreamResult, nothing happens in the browser.
I am seeking advice on how to resolve this issue and make it functional. Any suggestions would be greatly appreciated.