Question

这是Project Silk中DDD的参考用法。

该项目使用DDD，并实施了处理程序和服务的概念。这两种类型的区别和用例究竟是什么？

例如，有一个服务UserServices用于创建用户。但车辆的创造是在Handler中完成的。

想知道这个决定背后的原因。

域\ UserServices

public class UserServices : IUserServices
    {
        private readonly IUserRepository userRepository;

        public UserServices(IUserRepository userRepository)
        {
            if (userRepository == null) 
                  throw new ArgumentNullException("userRepository");
            this.userRepository = userRepository;
        }


        public User CreateUser(User newUser)
        {
            if (newUser == null) throw new ArgumentNullException("newUser");
            try
            {
                Model.User userToAdd = ToDataModelUser(newUser);
                this.userRepository.Create(userToAdd);
                return ToServiceUser(userToAdd);
            }
            catch (InvalidOperationException ex)
            {
                throw new BusinessServicesException
                            (Resources.UnableToCreateUserExceptionMessage, ex);
            }
        }
    }

域\处理程序\ CreateVehicle.cs

public class CreateVehicle
    {
        private readonly IVehicleRepository _vehicleRepository;
        private readonly IVehiclePhotoRepository _photoRepository;

        public CreateVehicle(IVehicleRepository vehicleRepository,
                 IVehiclePhotoRepository photoRepository)
        {
            _vehicleRepository = vehicleRepository;
            _photoRepository = photoRepository;
        }

        public virtual void Execute(int userId, 
                         ICreateVehicleCommand vehicleForm,  
                          HttpPostedFileBase photoFile)
        { 

            if (vehicleForm == null) throw 
                           new ArgumentNullException("vehicleForm");

            try
            {
                var vehicle = vehicleForm.ConvertToEntity(userId);
                _vehicleRepository.Create(userId, vehicle);

                if (photoFile == null) return;

                // the double reference between vehicle and photo 
               //is a potential source of pain
                var photo = photoFile.ConvertToEntity();
                _photoRepository.Create(vehicle.VehicleId, photo);
                vehicle.PhotoId = photo.VehiclePhotoId;

                _vehicleRepository.Update(vehicle);
            }
            catch (InvalidOperationException ex)
            {
                throw new BusinessServicesException  
                    (Resources.UnableToCreateVehicleExceptionMessage, ex);
            }
        }
    }

Answer 1

在您的示例中，我认为区别在于用户的创建是用户的主动操作，而viecle的创建是被动的。有人提交表单来创建用户，另一方面，它会在某些操作完成后触发创建viecle（可能是在创建用户之后？）。

也许您会对此answer感兴趣。

Project Silk中的域处理程序和应用程序服务有什么区别？

1 个答案: