Unit of Work Pattern: Handling Transactions Like a Pro in .NET

In modern .NET applications, handling database transactions efficiently is crucial for data consistency and integrity. The Unit of Work (UoW) pattern is a widely used design pattern that helps manage transactions, reduce redundant database calls, and improve code maintainability. Whether you're working with Entity Framework Core, Dapper, or other ORM tools, understanding this pattern can significantly enhance the way you handle data persistence.

In this article, we'll explore the Unit of Work pattern in .NET, its benefits, and how to implement it effectively. By the end, you'll have a solid grasp of how to use UoW for transactional consistency and performance optimization.

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What is the Unit of Work Pattern?

The Unit of Work pattern is a design pattern that groups multiple database operations (CRUD operations) into a single transaction. It ensures that all operations succeed or none of them are applied, thereby maintaining data integrity.

Key Responsibilities:

• Tracks changes: Keeps track of database operations.
• Commits transactions: Ensures all operations are committed successfully.
• Rollbacks transactions: Reverts changes if an operation fails.
• Reduces redundant operations: Minimizes unnecessary database hits.

When to Use the Unit of Work Pattern

• When working with multiple repositories that modify related data.
• When consistency and atomicity are crucial (e.g., banking transactions, order processing, etc.).
• When minimizing database calls is necessary for performance optimization.

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Implementing Unit of Work in .NET

Let's go step by step to implement the Unit of Work pattern using Entity Framework Core.

1. Define the Repository Interface

Repositories abstract database access logic for a specific entity.

public interface IRepository<T> where T : class
{
    Task<T> GetByIdAsync(int id);
    Task<IEnumerable<T>> GetAllAsync();
    Task AddAsync(T entity);
    void Update(T entity);
    void Delete(T entity);
}

2. Implement the Repository

public class Repository<T> : IRepository<T> where T : class
{
    protected readonly DbContext _context;
    private readonly DbSet<T> _dbSet;

    public Repository(DbContext context)
    {
        _context = context;
        _dbSet = context.Set<T>();
    }

    public async Task<T> GetByIdAsync(int id) => await _dbSet.FindAsync(id);
    public async Task<IEnumerable<T>> GetAllAsync() => await _dbSet.ToListAsync();
    public async Task AddAsync(T entity) => await _dbSet.AddAsync(entity);
    public void Update(T entity) => _dbSet.Update(entity);
    public void Delete(T entity) => _dbSet.Remove(entity);
}

3. Define the Unit of Work Interface

public interface IUnitOfWork : IDisposable
{
    IRepository<Product> Products { get; }
    IRepository<Order> Orders { get; }
    Task<int> CompleteAsync();
}

4. Implement the Unit of Work

public class UnitOfWork : IUnitOfWork
{
    private readonly ApplicationDbContext _context;
    public IRepository<Product> Products { get; private set; }
    public IRepository<Order> Orders { get; private set; }

    public UnitOfWork(ApplicationDbContext context)
    {
        _context = context;
        Products = new Repository<Product>(_context);
        Orders = new Repository<Order>(_context);
    }

    public async Task<int> CompleteAsync() => await _context.SaveChangesAsync();

    public void Dispose() => _context.Dispose();
}

5. Using the Unit of Work in a Service Layer

public class OrderService
{
    private readonly IUnitOfWork _unitOfWork;
    
    public OrderService(IUnitOfWork unitOfWork)
    {
        _unitOfWork = unitOfWork;
    }

    public async Task PlaceOrderAsync(Order order)
    {
        await _unitOfWork.Orders.AddAsync(order);
        await _unitOfWork.CompleteAsync();
    }
}

6. Registering Unit of Work in Dependency Injection

services.AddScoped<IUnitOfWork, UnitOfWork>();

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Advantages of Using the Unit of Work Pattern

✅ Ensures Transaction Consistency: Either all changes are committed, or none. ✅ Encapsulates Database Operations: Hides the complexity of transactions. ✅ Reduces Database Calls: Combines operations to minimize interactions. ✅ Improves Code Maintainability: Follows the Single Responsibility Principle.

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Common Mistakes to Avoid

🚨 Forgetting to Call CompleteAsync(): Changes won’t be persisted. 🚨 Not Disposing of the Unit of Work: Can cause memory leaks. 🚨 Using Repositories Without UoW: Leads to multiple disconnected transactions.

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Frequently Asked Questions (FAQs)

1. How is the Unit of Work Pattern different from the Repository Pattern?

The Repository Pattern provides a way to access data, while the Unit of Work manages transactional consistency across multiple repositories.

2. Is Unit of Work necessary for Entity Framework Core?

EF Core already tracks changes, but using UoW ensures explicit transactional control, especially when working with multiple repositories.

3. Can I use Unit of Work with Dapper?

Yes! You need to handle transactions manually using IDbTransaction.

4. Does Unit of Work work with CQRS?

Yes, but CQRS separates read and write operations, so UoW is typically applied only to the write side.

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Conclusion

The Unit of Work pattern is a powerful way to manage database transactions in .NET applications. It ensures data consistency, reduces redundant calls, and improves maintainability. By implementing this pattern, you gain full control over transactions and can handle database operations like a pro!

What’s Next?

🚀 Implement the Unit of Work pattern in your next .NET project.💬 Drop your questions and thoughts in the comments!

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