How do I download a file using memorystream?

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I need to download an Excel file named "Book1.xlsx" from wwwroot folder when I click a Download button.

HTML

<button type="button" class="btn btn-primary" @onclick="DownloadSingleFile">Download</button>

I have tried the below code. But it is showing error - File cannot be used like a method.

What I have tried:

C#

private void DownloadSingleFile()
   {
       var path = Path.Combine(Directory.GetCurrentDirectory(), "wwwroot", "Book1.xlsx");
       var memory = new MemoryStream();
       if (System.IO.File.Exists(path))
       {
           var net = new System.Net.WebClient();
           var data = net.DownloadData(path);
           var content = new System.IO.MemoryStream(data);
           memory = content;
       }
       memory.Position = 0;
       File(memory.ToArray(), "application/vnd.ms-excel", "Book1.xlsx");
   }

Thanks!

Posted 19-Oct-23 1:55am

Rajesh Kumar 2013

Updated 19-Oct-23 4:57am

Deeksha Shenoy

v4

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M Imran Ansari · Accepted Answer · 2023-10-19T02:02:00

I'm assuming, you are working with ASP.NET Core application, to download a file from the wwwroot folder when a button is clicked, you can use the PhysicalFile method and return a FileContentResult from the controller.
Here's an example:

C#

using Microsoft.AspNetCore.Mvc;
using System.IO;
public IActionResult DownloadSingleFile()
{
    var path = Path.Combine(Directory.GetCurrentDirectory(), "wwwroot", "Book1.xlsx");

    if (System.IO.File.Exists(path))
    {
        var memory = new MemoryStream();
        using (var stream = new FileStream(path, FileMode.Open))
        {
            stream.CopyTo(memory);
        }
        memory.Position = 0;
        return File(memory, "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet", Path.GetFileName(path));
    }
    else
    {
        return NotFound();
    }
}

This method reads the file from the wwwroot folder, copies it to a memory stream, and then returns it as a file download. The File method is used to return the file content as an application/vnd.openxmlformats-officedocument.spreadsheetml.sheet (MIME type for Excel files) to the client.
Make sure you have configured your routing properly to ensure the DownloadSingleFile method is correctly mapped to the corresponding URL.