🏗️ Clean Architecture + Repository & Service Patterns in .NET (Made Practical)
🏗️ Clean Architecture in .NET (Made Practical)
Imagine you’re building a house 🏠 —
you wouldn’t run electrical wiring through the bathroom plumbing, right?
Everything has a purpose and stays organized.
That’s exactly what Clean Architecture does for your codebase.
🔹 The Core Idea
Separate your code into independent layers:
1️⃣ Domain → The heart ❤️ — business rules, entities, and interfaces.
2️⃣ Application → Use cases (e.g., CreateOrder, CalculateDiscount).
3️⃣ Infrastructure → Where data lives — EF Core, API calls, file systems.
4️⃣ Presentation → API controllers, Razor Pages, or Angular UI.
👉 Rule: Outer layers can depend on inner layers, but never the other way around.
⚙️ Repository Pattern
Your Repository acts as a translator between the database and your application.
Instead of sprinkling SQL or EF queries across services:
var user = _userRepository.GetById(5);
Now, if you ever switch from SQL Server to MongoDB, only the repository changes —
the rest of the app stays intact. 🔄
✅ Keeps data logic in one place.
✅ Improves testability with interfaces like IUserRepository.
⚙️ Service Pattern
Your Service layer owns the business logic — rules, validation, and decisions.
Example:
public class OrderService {
public void PlaceOrder(Order order) {
// Check stock, calculate discounts, handle payment, etc.
}
}
Controllers just call the service — they don’t make business decisions.
That’s how you keep controllers thin and logic reusable.
💡 Practical Tip
In a real .NET solution:
/Domain
└── Entities, Interfaces
/Application
└── DTOs, Services
/Infrastructure
└── Repositories, EF Context
/Presentation
└── Controllers, Views
Each project references only what it needs —
this makes refactoring or scaling painless.
🚀 Key Takeaway
Repository → Handles data access
Service → Handles business logic
Controller → Handles API or UI requests
Together, they create a structure that’s clean, testable, and future-proof.
