In today's digital age, file downloads are an integral part of web applications, enabling users to access and share content efficiently. In this blog post, we will delve into the process of downloading multiple files in a compressed Zip format using ASP.NET Core Web API. By the end of this tutorial, you'll have a clear understanding of how to implement a straightforward and reliable file download mechanism in your web application.

Prerequisites

Before we dive into the implementation, let's ensure that you have the following prerequisites:

1. Basic understanding of C# and ASP.NET Core.
2. Visual Studio or any other preferred code editor installed.
3. ASP.NET Core Web API project set up.

Step 1: Setup the Project

To begin, create a new ASP.NET Core Web API project or use an existing one. If you're creating a new project, ensure you have the necessary dependencies installed.

Step 2: Install Required Packages

We need to install the "System.IO.Compression" package to work with Zip files. To do this, open the Package Manager Console and run the following command:

Install-Package System.IO.Compression -Version 4.3.0

Step 3: Create the File Download Endpoint

Next, let's create an endpoint in the Web API that will handle the file download. In the desired controller, add the following method:

[HttpGet]

[Route("api/downloadfiles")]

public IActionResult DownloadFiles()

{

  var files = new List<string>

  {

    "file1.txt",

    "file2.pdf",

    "file3.png"

    // Add the file paths you want to include in the Zip here.

  };

  using (var memoryStream = new MemoryStream())

  {

    using (var zipArchive = new ZipArchive(memoryStream, ZipArchiveMode.Create, true))

    {

      foreach (var file in files)

      {

        var entry = zipArchive.CreateEntry(file);

        using (var entryStream = entry.Open())

        using (var fileStream = new FileStream(file, FileMode.Open))

        {

          fileStream.CopyTo(entryStream);

        }

      }

    }

    memoryStream.Seek(0, SeekOrigin.Begin);

    return File(memoryStream, "application/octet-stream", "Files.zip");

  }

}

Step 4: Test the Endpoint

Build and run your Web API project. Use your favorite API testing tool (e.g., Postman) or a web browser to access the "api/downloadfiles" endpoint. You should receive a prompt to download the "Files.zip" file, which will contain all the specified files in the Zip format.

In this blog post, we explored how to implement a simple file download mechanism in Zip format using ASP.NET Core Web API. The provided code snippet allows you to compress multiple files into a single downloadable Zip file effortlessly. This feature is particularly useful when you need to provide users with multiple files in a compact and organized manner.

Remember to handle any potential errors and validate user input when implementing this in a production environment. Additionally, you can extend this functionality by accepting user preferences for file selection or compressing files from various sources.

Feel free to adapt and enhance this solution to meet the specific requirements of your project. Happy coding!