Unit of Work & Repository Pattern in C#

Have you ever worked on a project and accidentally messed up your database?
I remember one time I was building an e-commerce app, and a user placed a new order. I tried adding it quickly, and boom - disaster struck.

That’s when I realized why Unit of Work and Repository Pattern are essential for clean, maintainable code in C# / .NET.

Why It Matters​

Here’s the problem:

Imagine your system needs to:

1. Add the Order to the Orders table
2. Decrease the quantity in the Products table
3. Record the payment in the Payments table

If any step fails - say the order saves but the quantity doesn’t decrease - your database becomes inconsistent.

This is where Unit of Work comes to the rescue.

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Unit of Work: The Hero​

Unit of Work groups all operations into one single transaction:

• Either all operations succeed
• Or if something fails, everything rolls back

Your database always stays consistent, and you avoid partial updates that can break your app.

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🏗 Repository Pattern: The Best Friend​

But how does Unit of Work know what to add or update? That’s where the Repository Pattern comes in.

Repositories act as mediators:

• Instead of writing SQL queries everywhere, you use clean objects like UserRepository or ProductRepository
• Your business logic doesn’t care what kind of database is behind the scenes - SQL Server, MongoDB, or even a CSV file
• The big win: your code becomes decoupled.

Example: tomorrow, if you switch ORMs or database types, you just update your Repositories. Your business logic stays untouched.

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🛠 How They Work Together​

Here’s a simple workflow:

1. Your business logic calls the UnitOfWork
2. From the UnitOfWork, you get the Repository you need
3. Use the Repository to add or update data
4. Call Complete() at the end

using (var unitOfWork = new UnitOfWork())
{
    var orderRepo = unitOfWork.OrderRepository;
    orderRepo.Add(newOrder);

    var productRepo = unitOfWork.ProductRepository;
    productRepo.Update(product);

    var paymentRepo = unitOfWork.PaymentRepository;
    paymentRepo.Add(payment);

    unitOfWork.Complete(); // Executes everything in one transaction
}

Everything is executed together. If anything fails, the transaction rolls back automatically.

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Isn’t DbContext Enough?​

If you’re using Entity Framework Core, you might think: “Doesn’t DbContext already do this?”

Yes, it does handle transactions.

But the catch: using DbContext directly ties your code forever to EF Core.

• Unit tests without a database? Very hard.
• Switching databases? Painful.

With Unit of Work + Repository, you abstract the ‘what’ from the ‘how’:

• What: Add a user or process an order (business logic)
• How: Save it in SQL Server, MongoDB, or a CSV file (implementation)

This separation makes your code clean, maintainable, and testable.

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Advantages for Developers​

• Consistent data: No partial updates
• Decoupled code: Business logic doesn’t care about database implementation
• Testable: You can mock repositories for unit tests
• Flexible: Easily switch ORMs or database types
• Clean architecture: Separation of concerns becomes natural

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Real-World Analogy​

Think of Unit of Work as a team leader and Repositories as team members:

• Team leader ensures all tasks are completed before final submission
• Repositories do the actual work (add, update, delete)
• If one member fails, the leader cancels everything and starts fresh

This is exactly how enterprise-grade applications avoid data corruption.

Final Thoughts​

Using Unit of Work and Repository Pattern is not just about coding style - it’s about preventing disasters, simplifying testing, and future-proofing your C# / .NET applications.

Next time you build something that interacts with multiple tables, think of them as your secret weapons

• Unit of Work = transaction manager
• Repository = abstraction layer

Your database will thank you, and your code will stay clean, modular, and maintainable.