带有 Ninject 的装饰器图案

本文关键字：Ninject 带有 | 更新日期: 2025-02-19 08:39:30

我正在尝试应用这种方法来制作验证包装器。我已经创建了以下接口，并且我正在使用Ninject作为我的DI容器

public interface ICommandHandler<TCommand>
    {
        void Handle(TCommand command);
    }
public interface IValidator<T>
{
    IEnumerable<ValidationResult> Validate(T command);
}
public class ValidationCommandHandlerDecorator<T>:ICommandHandler<T>
{
    private readonly ICommandHandler<T> _decoratee;
    private readonly IValidator<T> _validator;
    public ValidationCommandHandlerDecorator(ICommandHandler<T> decoratee,IValidator<T> validator )
    {
        _decoratee = decoratee;
        _validator = validator;
    }
    public void Handle(T command)
    {
        this._validator.Validate(command);
        this._decoratee.Handle(command);
    }
}
public class SaveNewOsiRequestController : ApiController
{
    private readonly ICommandHandler<OsiRequest> _osiRequestSaveHandler;
    public SaveNewOsiRequestController(ICommandHandler<OsiRequest> osiRequestSaveHandler)
    {
        _osiRequestSaveHandler = osiRequestSaveHandler;
    }
}

以下是我将具体类注入控制器的方式：

        kernel.Bind(typeof (IValidator<>)).To(typeof (OsiRequestValidator));
        kernel.Bind(typeof (ICommandHandler<>))
            .To(typeof (SaveOsiRequestCommandHandler))
            .WhenInjectedInto(typeof (ValidationCommandHandlerDecorator<>));
        kernel.Bind(typeof (ICommandHandler<>))
            .To(typeof (ValidationCommandHandlerDecorator<>))
            .WhenInjectedInto(typeof(SaveNewOsiRequestController));

代码工作正常，没有任何问题。但是，问题是我如何使用Ninject为另一个控制器进行相同的注入？为了简单起见，我想将另一个Validator和另一个CommandHandler注入另一个Controller，如下所示：

        kernel.Bind(typeof (IValidator<>)).To(typeof (ANOTHER_Validator));
        kernel.Bind(typeof (ICommandHandler<>))
            .To(typeof (ANOTHER_CommandHandler))
            .WhenInjectedInto(typeof (ValidationCommandHandlerDecorator<>));
        kernel.Bind(typeof (ICommandHandler<>))
            .To(typeof (ValidationCommandHandlerDecorator<>))
            .WhenInjectedInto(typeof(ANOTHER_RequestController));

带有 Ninject 的装饰器图案

这里的问题是您正在执行泛型绑定，但您在特定情况下使用它。 仅当希望泛型绑定应用于该绑定的所有情况(或至少可以有条件绑定到的所有情况(时，才希望使用泛型绑定。

为此，您可以同样轻松地执行此操作：

kernel.Bind<IValidator<OsiRequest>>().To<OsiRequestValidator>();
kernel.Bind<ICommandHandler<OsiRequest>()
        .To<SaveOsiRequestCommandHandler>()
        .WhenInjectedInto<ValidationCommandHandlerDecorator<OsiRequest>>();
kernel.Bind<ICommandHandler<OsiRequest>()
        .To<ValidationCommandHandlerDecorator<OsiRequest>()
        .WhenInjectedInto<SaveNewOsiRequestController>();

然后每个额外的将是：

kernel.Bind<IValidator<DifferentRequest>>().To<DifferentValidator>();
kernel.Bind<ICommandHandler<DifferentRequest>()
        .To<DifferentRequestCommandHandler>()
        .WhenInjectedInto<ValidationCommandHandlerDecorator<DifferentRequest>>();
kernel.Bind<ICommandHandler<DifferentRequest>()
        .To<ValidationCommandHandlerDecorator<DifferentRequest>()
        .WhenInjectedInto<DifferentRequestController>();

您可以更改最后一个绑定，这样就不必为每个类型声明它：

kernel.Bind(typeof (ICommandHandler<>))
        .To(typeof (ValidationCommandHandlerDecorator<>))
        .WhenInjectedInto<ApiController>();
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