ASP.NET Core Minimal API — Complete Guide

In this tutorial, you'll learn about ASP.NET Core Minimal API. We cover key concepts, practical examples, and best practices to help you understand and apply this topic effectively.

You create a Controller class with a single action that just returns data. The class, constructor, and attribute ceremony outweigh the actual logic.

Wrong

[ApiController]
[Route("api/products")]
public class ProductsController : ControllerBase
{
    [HttpGet]
    public IActionResult GetProducts()
    {
        return Ok(new[] { new { Id = 1, Name = "Laptop" } });
    }
}

Right

// Program.cs
var builder = WebApplication.CreateBuilder(args);
var app = builder.Build();

app.MapGet("/api/products", () =>
    new[] { new { Id = 1, Name = "Laptop" } });

app.Run();

With parameters:

app.MapGet("/api/products/{id}", (int id) =>
    Results.Ok(new { Id = id, Name = "Laptop" }));

app.MapPost("/api/products", (Product product) =>
    Results.Created($"/api/products/{product.Id}", product));

Prevention

• Use minimal APIs for simple, focused endpoints.
• Use Results helpers for typed results.
• Use Dependency Injection via parameters.
• Use app.MapGroup for route groups.
• Use app.MapMethods for specific HTTP methods.

Common Mistakes with core minimal api

1. Placing the wildcard pattern first in case expressions, making all subsequent patterns unreachable
2. Using head and tail instead of pattern matching, causing runtime errors on empty lists
3. Forgetting that lazy evaluation defers computation until the value is forced, causing space leaks with unevaluated thunks

These mistakes appear frequently in real-world ASPNET code. DodaTech's contributors have identified these patterns through analysis of open-source projects and production systems.

Practice Exercise

Write a pure function that safely divides two integers using Maybe, then test it with edge cases like division by zero and negative numbers.

This exercise reinforces the concepts covered in this guide. Try implementing it before checking online solutions.

FAQ

When should I use minimal API vs controllers?

Learn more at DodaTech.