Blog
Mert Özen's blog posts on software development, backend, frontend, and DevOps.
Introduction to Web APIs with .NET 9: REST principles and why .NET?
The first article of the .NET 9 Web API series. We cover REST principles, resource-oriented thinking, HTTP methods, and why we chose .NET 9, in a plain, example-driven style.
Setting up the initial project: project structure, Program.cs, and a minimal hosting model.
We set up our first .NET 9 Web API project. We break down Program.cs line by line, and understand the minimal hosting model, the builder-versus-app split, and why middleware order matters.
Controllers or Minimal APIs? When to Choose Which
We compare two ways of writing endpoints in .NET 9: controller-based structure and Minimal APIs. When each makes sense and what the real difference is, made clear with examples.
Writing Your First Controller: Routing, Attributes and Action Methods
We write our first real controller. How routing works, what attributes do, how action methods are built, and how an incoming request reaches the right method, step by step.
HTTP Status Codes and Returning the Right Response: IActionResult and Results
We cover HTTP status codes and the ways to return the right response. Which code for which situation, the difference between IActionResult and Results, and small details that help API consumers.
Model Binding: Binding Request Data to Your Method (Route, Query, Body, Header)
We cover how .NET automatically binds request data to your method parameters: reading from the route, query string, body and headers, attributes like [FromBody], and common mistakes.
What Is a DTO and Why Shouldn't We Return the Entity Directly?
We cover what DTOs are and why you shouldn't return database objects directly: the concrete benefits of using DTOs for security, privacy, flexibility, and contract stability.
Model Validation: Validating Incoming Data with Data Annotations and FluentValidation
We cover validating incoming data: defining quick rules with Data Annotations, the automatic validation of [ApiController], and FluentValidation for complex rules. What to choose and when?
Introduction to Entity Framework Core: DbContext and Your First Migration
We start storing our data in a real database. What EF Core is, what DbContext represents, how tables are defined with DbSet, and how the database is created with the first migration, step by step.
Is the Repository Pattern Really Necessary? Let's Talk About the Service Layer
We discuss placing a layer between the controller and DbContext instead of using it directly. What the service layer is for, whether the repository pattern is really necessary, and when it pays off.
DTO-Entity Conversion: Writing It by Hand or Using AutoMapper?
We discuss the conversion between entity and DTO. The upsides of manual mapping, when AutoMapper is a convenience and when a hidden cost, and a practical look at which to choose in your project.
Dependency Injection in Depth: Singleton, Scoped and Transient Lifetimes
We cover the lifetime concept at the heart of dependency injection. The difference between singleton, scoped and transient, when to use each, and the subtle bugs a wrong choice causes.