EF Core如何实现工作单元模式 EF Core工作单元(Unit of Work)教程

public interface IUnitOfWork : IDisposable
{
    DbContext Context { get; }
    Task SaveChangesAsync(CancellationToken cancellationToken = default);
    void BeginTransaction();
    void Commit();
    void Rollback();
}

public class UnitOfWork : IUnitOfWork
{
    private readonly DbContext _context;
    private IDbContextTransaction _transaction;

    public UnitOfWork(DbContext context) => _context = context;

    public DbContext Context => _context;

    public async Task SaveChangesAsync(CancellationToken cancellationToken = default)
        => await _context.SaveChangesAsync(cancellationToken);

    public void BeginTransaction() => 
        _transaction ??= _context.Database.BeginTransaction();

    public void Commit()
    {
        _transaction?.Commit();
        _transaction?.Dispose();
        _transaction = null;
    }

    public void Rollback()
    {
        _transaction?.Rollback();
        _transaction?.Dispose();
        _transaction = null;
    }

    public void Dispose() => _transaction?.Dispose();
}

services.AddScoped();
services.AddDbContext(options => 
    options.UseSqlServer(connectionString));

public class OrderService
{
    private readonly IUnitOfWork _unitOfWork;
    private readonly IOrderRepository _orderRepo;
    private readonly IProductRepository _productRepo;

    public OrderService(
        IUnitOfWork unitOfWork,
        IOrderRepository orderRepo,
        IProductRepository productRepo)
    {
        _unitOfWork = unitOfWork;
        _orderRepo = orderRepo;
        _productRepo = productRepo;
    }

    public async Task PlaceOrderAsync(Order order)
    {
        _unitOfWork.BeginTransaction();
        try
        {
            await _orderRepo.AddAsync(order);
            var product = await _productRepo.GetByIdAsync(order.ProductId);
            product.Stock -= order.Quantity;

            await _unitOfWork.SaveChangesAsync();
            _unitOfWork.Commit();
        }
        catch
        {
            _unitOfWork.Rollback();
            throw;
        }
    }
}