Explain Middleware in ASP.NET Core with Simple Example
👋 Introduction
Hey hey! 👋
So you’ve been building your ASP.NET Core app and suddenly this thing called Middleware pops up… 😳 You’re like, “Wait… what is that?”
Well guess what? You’re not alone, buddy. Everyone asks that question at some point.
Today, I’ll explain Middleware in ASP.NET Core in the simplest way possible. No jargon. No confusion. Just real talk and fun examples. 😄
Ready to become a middleware master? Let’s go! 💪
📚 What You Are Going to Learn in This Lesson
✔️ What is Middleware and why we use it
✔️ How Middleware works in ASP.NET Core
✔️ Order of Middleware and why it matters
✔️ How to write your own custom Middleware
✔️ Real-life example with code
✔️ Debugging and playing with Middleware
Sounds cool? 🎧 Let’s jump in!
🧠 What is Middleware in ASP.NET Core?
Alright. Let’s explain Middleware in ASP.NET Core like this…
Imagine a line of people, and each one adds something to a burger 🍔 before passing it to the next person. That’s exactly what middleware does — but with HTTP requests!
Each middleware is like a step in the request pipeline. It can:
- 🔍 Look at the request
- 🛠️ Modify it
- 🧾 Pass it on
- ❌ Or even stop it right there
So, when a browser asks for your website, the request goes through each middleware one by one. Like a relay race! 🏃🏽
🧱 How Middleware Works
Let’s explain Middleware in ASP.NET Core with a basic example:
Here’s what it looks like in Program.cs:
var builder = WebApplication.CreateBuilder(args);
var app = builder.Build();
app.Use(async (context, next) =>
{
Console.WriteLine("👋 Middleware 1 - Before");
await next.Invoke();
Console.WriteLine("👋 Middleware 1 - After");
});
app.Use(async (context, next) =>
{
Console.WriteLine("🚀 Middleware 2 - Before");
await next.Invoke();
Console.WriteLine("🚀 Middleware 2 - After");
});
app.Run(async context =>
{
Console.WriteLine("✅ Final Middleware");
await context.Response.WriteAsync("Hello from the last middleware!");
});
app.Run();
🧠 Let’s Break It Down
Use()is for middleware that passes control to the next stepRun()is the final step – it doesn’t callnext()- The order matters a lot. It’s like stacking pancakes – what’s on top runs first! 🥞
So in this case, the output would be:
👋 Middleware 1 - Before
🚀 Middleware 2 - Before
✅ Final Middleware
🚀 Middleware 2 - After
👋 Middleware 1 - After
Cool, right? 😎 That’s the magic of the middleware pipeline!
✍️ Write Your Own Custom Middleware
Let’s say you want to log every request. Here’s a custom middleware:
public class RequestLoggerMiddleware
{
private readonly RequestDelegate _next;
public RequestLoggerMiddleware(RequestDelegate next)
{
_next = next;
}
public async Task Invoke(HttpContext context)
{
Console.WriteLine($"📢 Requested: {context.Request.Path}");
await _next(context);
}
}
And now, plug it in like this:
app.UseMiddleware<RequestLoggerMiddleware>();
🎉 Boom! You made your own middleware! Now every request will log the path in the terminal.
🛑 Why Order of Middleware Matters
Let’s explain Middleware in ASP.NET Core with a fun warning:
👉 Middleware is order-sensitive. If you mess up the order, things might break.
For example:
- If you add error handling after the middleware that fails, it won’t work 😬
- If you add static file support after authentication, static files might require login! 😅
So always plan the order like you’re building a burger… buns, sauce, patty, cheese… not cheese, then patty, then plate. 🍔😂
🧩 Real Life Middleware You Already Use
Here are some built-in middleware you’ll use all the time:
UseRouting()– Enables routingUseAuthentication()– Handles loginUseAuthorization()– Checks permissionsUseStaticFiles()– Serves images, CSS, JSUseEndpoints()– Maps the request to Razor Pages, MVC, or APIs
And yes… you can still explain Middleware in ASP.NET Core like this to your teammates and sound super smart! 😄💡
🤔 Common Mistakes to Avoid
❌ Skipping await next() — means later middleware never runs
❌ Wrong order of middleware — causes weird bugs
❌ Forgetting to call UseRouting() before UseEndpoints()
So go slow, test often, and don’t be afraid to break things while learning! 💥 That’s how we all grow.
🧭 Next What?
Alrighty friend, now you totally get it! You can proudly explain Middleware in ASP.NET Core like a boss! 🙌
But the journey doesn’t end here…
👉 In the next chapter, you’ll learn all about Dependency Injection in ASP.NET Core — what it is, why it matters, and how to use it like a pro! 🧪
Until then, keep experimenting with middleware and have fun breaking things! 😄💥
Need help with your code? Got stuck? Just holler! I’m always here to help! 👨🏫👩💻
