In this article I will explain with an example, how to use FileStreamResult in ASP.Net Core (.Net Core 8) MVC.
This article will illustrate how to download files using FileStreamResult class in ASP.Net Core (.Net Core 8) MVC.
FileStreamResult class is used when Stream (MemoryStream or FileStream) needs to be downloaded as File.
Note: For beginners in ASP.Net Core (.Net Core 8) MVC, please refer my article ASP.Net Core 8: Hello World Tutorial with Sample Program example.
 
 

Folder (Directory) Location

The Folder (Directory) is located within the Project inside the wwwroot folder. Below is the screenshot of the Solution Explorer window where you can see the Folder (Directory) i.e. Files and it containing three files.
FileStreamResult .Net Core Example: Using FileStreamResult in ASP.Net Core MVC
 
 

Model

Following is a Model class named FileModel with one property i.e. FileName.
public class FileModel
{
    public string FileName { get; set; }
}
 
 

Namespaces

You will need to import the following namespaces.
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.StaticFiles;
using MVC_Core_FileStreamResult.Models;
 
 

Controller

The Controller consists of following Action methods.

Action method for handling File Display operation

Inside this Action method, the list of all files in the Files Folder (Directory) (present in the wwwroot Folder) is fetched using the IWebHostingEnvironment interface into a String Array using the GetFiles method of the Directory class.
Note: For more details about IWebHostEnvironment interface, please refer Using IWebHostEnvironment in ASP.Net Core.
 
Then values of the Array are copied to a Generic List collection consisting objects of FileModel class and then returned to the View.
 

Action method for handling File Download operation

This action method handles the File Download operation and when the ActionLink is clicked, the name of the File to be downloaded is sent to this method.
Then, File is read as Stream in FileStream Class object.
Finally, the FileStream class object is sent for download using an object of FileStreamResult class.
public class HomeController : Controller
{
    private IWebHostEnvironment Environment;
 
    public HomeController(IWebHostEnvironment _environment)
    {
        Environment = _environment;
    }
 
    public IActionResult Index()
    {
        //Fetch all files in the Folder (Directory).
        string[]filePaths  = Directory.GetFiles(Path.Combine(this.Environment.WebRootPath, "Files/"));
 
        //Copy File names to Model collection.
        List<FileModel> files = new List<FileModel>();
        foreach (string  filePath in filePaths)
        {
            files.Add(new FileModel { FileName = Path.GetFileName(filePath) });
        }
 
        return View(files);
    }
 
    public FileStreamResult DownloadFile(string fileName)
    {
        //Determine the Content Type of the File.
        string contentType = "";
        new FileExtensionContentTypeProvider().TryGetContentType(fileName, out contentType);
 
        //Build the File Path.
        string path = Path.Combine(this.Environment.WebRootPath,"Files/") + fileName;
 
        //Read the File data into FileStream.
        FileStream fileStream = new FileStream(path,FileMode.Open, FileAccess.Read);
 
        //Send the File to Download.
        return new FileStreamResult(fileStream, contentType);
    }
}
 
 

View

Inside the View, the FileModel class is declared as List which specifies that it will be available as a Collection.

Displaying the Files

For displaying the files, an HTML Table is used. A LOOP will be executed over the Model which will generate the HTML Table rows with the File records.
 

Downloading the File

The HTML Table contains an ActionLink for downloading the File.
When the Download link is clicked, the ActionLink calls the DownloadFile Action method and the File is downloaded.
@using MVC_Core_FileStreamResult.Models
@model List<FileModel>
 
@{
    Layout = null;
}
 
<!DOCTYPE html>
 
<html>
<head>
    <meta name="viewport" content="width=device-width" />
    <title>Index</title>
</head>
<body>
    <table>
        <tr>
            <th>File Name</th>
            <th></th>
        </tr>
        @foreach (FileModel file in Model)
        {
            <tr>
                <td>@file.FileName</td>
                <td>@Html.ActionLink("Download", "DownloadFile", new { fileName = file.FileName })</td>
            </tr>
        }
    </table>
</body>
</html>
 
 

Screenshot

FileStreamResult .Net Core Example: Using FileStreamResult in ASP.Net Core MVC
 
 

Downloads

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