Chapter 19: File Uploads in C#

Multipart form data and file handling. In this chapter, you will learn file uploads in depth with C# code examples, explanations, and best practices.

Overview

This chapter covers file uploads for Kungfu.js developers using C#. We will start with the basics, move through practical examples, and end with advanced techniques and common pitfalls.

Why This Matters

Understanding file uploads is essential because it is a core part of building web applications. Every real-world app needs to handle multipart form data and file handling. Skipping this chapter would leave a gap in your knowledge that would cause problems later.

Code Example

Here is how to handle requests and responses in C#:

// Handle file upload (multipart/form-data)
app.post('/upload', (req) => {
    // req.body contains multipart form data
    // Parse it to extract files
    // The Rust core handles the multipart parsing
    return { status: 201, body: 'File uploaded' };
});

Common Mistakes

• Not reading the documentation: Always check the API reference when something does not work as expected.
• Skipping security: Never disable the default middleware unless you have a very good reason. Security is not optional.
• Not testing: Write tests for your handlers. Kungfu.js makes this easy with the built-in test utilities.

Summary

In this chapter, you learned about file uploads in C#. You saw code examples, understood how things work under the hood, and learned about common mistakes to avoid.

What is Next?

In chapter 20, we will cover Cookies and Sessions: Set cookies, manage sessions, SameSite.