Blog
Mert Özen's blog posts on software development, backend, frontend, and DevOps.
Authentication and Authorization: The Difference Between Identity Verification and Permission
We separate two concepts most developers confuse: authentication (who are you?) and authorization (what are you allowed to do?). The difference, the correct order, and how these are positioned in .NET.
API Versioning: Evolving Your API Without Breaking Old Clients
We cover how not to break old clients while evolving the API over time: what a breaking change is, why versioning is needed, the URL/header/query methods, and setting up versioning in .NET.
Configuration and the Options Pattern: appsettings Layers and Separating Settings from Code
We cover separating settings from code: appsettings files and environment layers, managing connection strings safely, reading settings with strong types via the Options pattern, and keeping secrets out of code.
Global Error Handling: Catching All Errors in a Single Place
We cover catching unexpected errors from anywhere in the app in a single place: escaping scattered try-catch blocks, setting up exception middleware, and returning a clean, safe response to the user.
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 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.
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.
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.
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.