通用存储库和事务

本文关键字：事务 存储 | 更新日期: 2023-09-27 18:30:03

我已经在MVC应用程序中实现了我的第一个Generic存储库。工作正常，但如何将存储库放入事务范围？

 public interface IRepository<TEntity> where TEntity : class
    {
        List<TEntity> FetchAll();
        IQueryable<TEntity> Query { get; }
        void Add(TEntity entity);
        void Delete(TEntity entity);
        void Save();
    }

    public class Repository<T> : IRepository<T> where T : class
    {
        private readonly DataContext _db;
        public Repository(DataContext db)
        {
            _db = db;
        }
        #region IRepository<T> Members
        public IQueryable<T> Query
        {
            get { return _db.GetTable<T>(); }
        }
        public List<T> FetchAll()
        {
            return Query.ToList();
        }
        public void Add(T entity)
        {
            _db.GetTable<T>().InsertOnSubmit(entity);
        }
        public void Delete(T entity)
        {
            _db.GetTable<T>().DeleteOnSubmit(entity);
        }
        public void Save()
        {
            _db.SubmitChanges();
        }
        #endregion
    }
        private void RegisterDependencyResolver()
        {
            var kernel = new StandardKernel();         
            var connectionString = ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString;
            kernel.Bind(typeof(DataContext)).ToMethod(context => new DataContext(connectionString));
            kernel.Bind(typeof(IRepository<>)).To(typeof(Repository<>));            
            DependencyResolver.SetResolver(new NinjectDependencyResolver(kernel));
        }

    public class AdminController : Controller
    {
        private readonly IRepository<User> _userRepository;
        private readonly IRepository<Order> _orderRepository;
public AdminController(IRepository<User> userRepository, IRepository<Order> orderRepository)
        {
            _userRepository = userRepository;
            _orderRepository = orderRepository;
        }



 public ActionResult InsertUser(UserViewModel model)
        {
//Skip Code
//Do not commit data to database if _orderRepository is failed to save data
       _userRepository.Add(user);
            _userRepository.Save();

//Skip Code
      _orderRepository.Add(order);
            _orderRepository.Save();
}

}

在InsertUser操作中，用事务范围包装存储库代码的最佳方法是什么？

通用存储库和事务

这里缺少一个抽象。您应该将所有业务逻辑放置在命令处理程序中，并创建一个实现事务行为的命令处理程序装饰器。本文介绍了如何做到这一点，但简而言之：

  1. 定义ICommandHandler<TCommand>接口：

    public interface ICommandHandler<TCommand>
{
    void Handle(TCommand command);
}

  2. 创建定义业务操作契约的命令。命令只是DTO（只有数据，没有行为）。例如：

    public class ShipOrderCommand
{
    public int OrderId { get; set; }
    public ShippingInfo Info { get; set; }
}

  3. 实现包含这些命令的业务逻辑/行为的命令处理程序：

    public class ShipOrderCommandHandler 
    : ICommandHandler<ShipOrderCommand>
{
    private readonly IRepository<Order> repository;
    public ShipOrderCommandHandler(
        IRepository<Order> repository)
    {
        this.repository = repository;
    }
    public void Handle(ShipOrderCommand command)
    {
        // do some useful stuf with the command and repository.
    }
}

  4. 让MVC控制器依赖于ICommandHandler<T>抽象：

    public ShipOrderController : Controller
{
    private readonly ICommandHandler<ShipOrderCommand> handler;
    public ShipOrderController(
        ICommandHandler<ShipOrderCommand> handler)
    {
        this.handler = handler;
    }
    public void Ship(int orderId, ShippingInfo info)
    {
        this.handler.Handle(new ShipOrderCommand
        {
            OrderId = orderId,
            Info = info
        });
    }
}

  5. 定义一个实现事务逻辑的通用装饰器：

    public TransactionalCommandHandlerDecorator<TCommand>
    : ICommandHandler<TCommand>
{
    private ICommandHandler<TCommand> decoratedHandler;
    public TransactionalCommandHandlerDecorator(
        ICommandHandler<TCommand> decoratedHandler)
    {
        this.decoratedHandler = decoratedHandler;
    }
    public void Handle(TCommand command)
    {
        using (var scope = new TransactionScope())
        {
            this.decoratedHandler.Handle(command);
            scope.Complete();
        }
    }
}

  6. 确保每个ShipOrderCommandHandler都用一个TransactionalCommandHandlerDecorator进行装饰并注入到ShipOrderController中。你可以用你最喜欢的DI容器，或者手动：

    protected override IController GetControllerInstance(
    RequestContext requestContext, Type controllerType)
{
    if (controllerType == typeof(ShipOrderController))
    {
        return new ShipOrderController(
            new TransactionalCommandHandlerDecorator<ShipOrderCommand>(
                new ShipOrderCommandHandler(
                    new OrderRepository())));
    }
    return base.GetControllerInstance(requestContext, controllerType);
}

有了这一点，您就可以在事务中运行所有业务逻辑，而不需要业务逻辑意识到这一点。

有一种模式叫做工作单元。这是一个解释。

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