Implementing the Unit of Work Pattern in Clean Architecture with .NET Core

Introduction

The Unit of Work pattern is a widely used design pattern that helps manage transactions and maintain data consistency in applications. When combined with Clean Architecture, it provides a solid foundation for building scalable and maintainable applications. In this article, we will explore how to implement the Unit of Work pattern in a .NET Core application within the context of Clean Architecture.

Understanding the Unit of Work Pattern

The Unit of Work pattern is used to manage transactions and ensure that multiple operations are treated as a single logical unit. It provides a way to group database operations together, ensuring that they either succeed or fail as a whole. The key principle behind the Unit of Work pattern is to maintain data consistency and integrity by committing or rolling back changes in a coordinated manner.

Integrating the Unit of Work Pattern in Clean Architecture

To implement the Unit of Work pattern in a .NET Core application within the context of Clean Architecture, follow these steps:

1. Define the Core Interfaces - Create an IUnitOfWork interface. This interface will define the contract for the Unit of Work, including methods like Commit() and Rollback().

2. Implement the Unit of Work Create a concrete implementation of the IUnitOfWork interface. This implementation will encapsulate the transactional boundaries and coordinate database operations. The Unit of Work implementation should provide methods for beginning a transaction, committing changes, and rolling back the transaction if needed.

3. Integrate with Repositories Modify your repository implementations to work with the Unit of Work. Each repository method should be wrapped within the Unit of Work’s transaction, ensuring that changes made by the repository are committed or rolled back together.

4. Application Layer Integration In the Application layer, inject the Unit of Work interface into the appropriate command or query handlers that require transactional operations. Within these handlers, perform the necessary operations using the repositories wrapped in the Unit of Work.

5. Unit of Work Usage When a command or query requires transactional operations, retrieve the Unit of Work instance through dependency injection. Begin the transaction using the Unit of Work’s method. Perform the required database operations using the repositories wrapped within the Unit of Work. Finally, call the Unit of Work’s Commit() method to persist the changes or the Rollback() method to discard the changes.

Practical Example

Let’s consider an example of a simple e-commerce application to illustrate the usage of the Unit of Work pattern.

Define the Unit of Work Interface:

public interface IUnitOfWork : IDisposable
{
    void Commit();
    void Rollback();
    IRepository<TEntity> GetRepository<TEntity>() where TEntity : class;
}

Implement the Unit of Work

public class UnitOfWork : IUnitOfWork
{
    private readonly DbContext _context;
    private Dictionary<Type, object> _repositories;

    public UnitOfWork(DbContext context)
    {
        _context = context;
        _repositories = new Dictionary<Type, object>();
    }

    public void Commit()
    {
        _context.SaveChanges();
    }

    public void Rollback()
    {
        // Rollback changes if needed
    }

    public IRepository<TEntity> GetRepository<TEntity>() where TEntity : class
    {
        if (_repositories.ContainsKey(typeof(TEntity)))
        {
            return (IRepository<TEntity>)_repositories[typeof(TEntity)];
        }

        var repository = new Repository<TEntity>(_context);
        _repositories.Add(typeof(TEntity), repository);
        return repository;
    }

    public void Dispose()
    {
        _context.Dispose();
    }
}

Integrate with Repositories

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

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

    // Implement repository methods...
}

Usage in Application Layer

public class ProductService
{
    private readonly IUnitOfWork _unitOfWork;
    private readonly IRepository<Product> _productRepository;

    public ProductService(IUnitOfWork unitOfWork)
    {
        _unitOfWork = unitOfWork;
        _productRepository = _unitOfWork.GetRepository<Product>();
    }

    public void CreateProduct(Product product)
    {
        // Perform business logic and repository operations using _productRepository...

        _unitOfWork.Commit();
    }
}

Conclusion

The Unit of Work pattern provides a robust mechanism for managing transactions and ensuring data consistency in .NET Core applications. By following the steps outlined in this article, you can leverage the benefits of the Unit of Work pattern to build scalable and maintainable applications.

The practical example demonstrated how the Unit of Work pattern can be integrated into an e-commerce application to handle database operations. With the Unit of Work pattern, developers can ensure that related operations are treated as a single logical unit, promoting data integrity and transactional consistency.