? 5 Mistakes I Made When Starting with .NET (and How to Avoid Them)

When I started working with .NET, I made several mistakes that made my code less efficient, harder to maintain, and even caused performance issues. If I had known about these pitfalls earlier, I would have saved a lot of time!

Here are 5 mistakes I made early in my .NET journey and how you can avoid them:

1?? Blocking Asynchronous Calls

?? One of the first mistakes I made was mixing synchronous and asynchronous code without understanding how async programming actually works. I tried calling async methods synchronously, which often resulted in deadlocks and unexpected application freezes.

? Wrong Code:

The problem here is that .Result blocks the main thread while waiting for the async method to complete, which can lead to deadlocks in environments with a synchronization context (like ASP.NET).

? Correct Code:

?? Tip: Always use await to keep the async flow and avoid unnecessary blocking.

2?? Using ORM Without Understanding SQL

?? At first, I thought Entity Framework (EF) would handle everything for me, and I wouldn't have to worry about SQL at all. But after analyzing auto-generated queries, I realized some of them were slow and inefficient. This directly affected my application’s performance.

? Wrong Code:

This may seem harmless, but depending on the data volume and the lack of indexes in the database, it can be very inefficient.

? Correct Code:

?? Tip:

• Use AsNoTracking() if you don’t need to modify the data. This improves performance.
• Always monitor EF-generated queries. In EF Core, you can use:

• For complex queries, consider optimizing with FromSqlRaw() and database indexing.

3?? Ignoring Dependency Injection

?? At first, I used to instantiate services directly inside classes, without considering coupling and testability. This made maintenance difficult and unit testing almost impossible.

? Wrong Code:

Here, OrderService directly depends on the concrete implementation of EmailService, making it difficult to replace this dependency with a mock in tests.

? Correct Code:

And in Program.cs (for .NET 6+):

?? Tip: Use .NET's dependency injection to keep your code modular and testable.

4?? Not Writing Automated Tests

?? In the beginning, I relied on the famous "it works on my machine", but when bugs started appearing in production, I realized the importance of automated tests.

? Wrong Code (no tests):

Without tests, any changes can break the code without anyone noticing.

? Correct Code (with tests using xUnit and FluentAssertions):

?? Tip: Start with unit tests, then add integration tests to cover full application flows.

5?? Poor Project Structure

?? At first, I mixed business logic, data access, and controllers, making the code hard to scale and maintain.

? Wrong Code (everything in the Controller):

This makes the controller directly responsible for database access, violating the separation of concerns principle.

? Correct Code (separating responsibilities):

?? Tip: Use a layered architecture to keep the code clean and scalable.

?? Conclusion: We all make mistakes when starting out, but the important thing is to learn and improve. Have you made any of these mistakes? Or do you have others to share? Drop a comment below!

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