问题：UI层之外的第一个对象是否接收并协调“控制”系统操作？
解决方案：将责任分配给表示以下选项之一的对象：
- - 表示整个“系统”，“根对象”，运行软件的设备或主要子系统（这些都是外观控制器的变体）
- -表示发生系统操作的用例场景（用例或会话控制器）
这个原则实现取决于我们系统的高级设计，但一般我们需要定义协调我们的业务事务处理的对象。乍一看，似乎Web应用程序/ API中的MVC控制器在这里是一个很好的例子（即使名称是相同的）但对我来说并非如此。当然它接收输入但它不应该协调系统操作 - 它应该将它委托给单独的服务或命令处理程序：public class CustomerOrdersController : Controller
{
private readonly IMediator _mediator;
public CustomerOrdersController(IMediator mediator)
{
this._mediator = mediator;
}
/// <summary>
/// Add customer order.
/// </summary>
/// <param name="customerId">Customer ID.</param>
/// <param name="request">Products list.</param>
[Route("{customerId}/orders")]
[HttpPost]
[ProducesResponseType((int)HttpStatusCode.Created)]
public async Task<IActionResult> AddCustomerOrder(
[FromRoute]Guid customerId,
[FromBody]CustomerOrderRequest request)
{
await _mediator.Send(new AddCustomerOrderCommand(customerId, request.Products));
return Created(string.Empty, null);
}
}
public class AddCustomerOrderCommandHandler : IRequestHandler<AddCustomerOrderCommand>
{
private readonly ICustomerRepository _customerRepository;
private readonly IProductRepository _productRepository;
private readonly IForeignExchange _foreignExchange;
public AddCustomerOrderCommandHandler(
ICustomerRepository customerRepository,
IProductRepository productRepository,
IForeignExchange foreignExchange)
{
this._customerRepository = customerRepository;
this._productRepository = productRepository;
this._foreignExchange = foreignExchange;
}
public async Task<Unit> Handle(AddCustomerOrderCommand request, CancellationToken cancellationToken)
{
// handling...
}
}
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