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Module 2: Minimal APIs (The Fast Food Stand)

📚 Module 2: Minimal APIs

Course ID: DOTNET-302
Subject: The Fast Food Stand

MVC (Module 1) is like a Fine Dining Restaurant. It has waiters, hosts, and many rooms. Minimal APIs are like a Fast Food Stand. It’s just one person, a grill, and a window. It’s significantly faster and has zero boilerplate.

🏗️ Step 1: The Boilerplate Problem

In MVC, to return a “Hello World” string, you need:

  1. A Controller class.
  2. A using Microsoft.AspNetCore.Mvc.
  3. A public IActionResult.
  4. A correctly named folder for your View.

Minimal APIs do it in one line.

🏗️ Step 2: The Map Command (The “Direct Order”)

In a Minimal API, you map the URL directly to a function.

🧩 The Analogy: The Drive-Thru

  • You drive up to the window (The URL /hello).
  • You say what you want.
  • They hand it to you instantly. No waiters, no menus, no table settings.

In Code:

var app = builder.Build();

// That's it! This is a complete API.
app.MapGet("/hello", () => "Hello from the Fast Food Stand!");

app.Run();

🏗️ Step 3: When to use Minimal APIs?

  1. Microservices: When your service only has 2 or 3 endpoints.
  2. Performance: Minimal APIs are about 10-20% faster than Controllers because they don’t have to “Look in the Mirror” (Reflection) as much.
  3. Modern Frontends: Perfect for React, Vue, or Blazor backends.

🧪 Step 4: Python Practice (C# vs. FastAPI)

If you have used FastAPI in Python, Minimal APIs will feel like home.

# FastAPI
@app.get("/items/{id}")
def read_item(id: int):
    return {"id": id}
// .NET Minimal API
app.MapGet("/items/{id}", (int id) => new { id });

🥅 Module 2 Review

  1. Minimal API: High-performance endpoints with zero classes or folders required.
  2. MapGet/MapPost: Routing your logic directly to a URL.
  3. Performance: The leanest way to build a web service in .NET.