依赖注入演示 [英] Dependency Injection for Presenter

问题描述

我有一个演示，需要一个服务和查看合同在其构造函数的参数：

I have a Presenter that takes a Service and a View Contract as parameters in its constructor:

public FooPresenter : IFooPresenter {
    private IFooView view;
    private readonly IFooService service;

    public FooPresenter(IFooView view, IFooService service) {
        this.view = view;
        this.service = service;
    }
}

我解决我的服务与Autofac：

I resolve my service with Autofac:

private ContainerProvider BuildDependencies() {
    var builder = new ContainerBuilder();
    builder.Register<FooService>().As<IFooService>().FactoryScoped();  

    return new ContainerProvider(builder.Build());  
}

在我的ASPX页面（View实现）：

In my ASPX page (View implementation):

public partial class Foo : Page, IFooView {
    private FooPresenter presenter;

    public Foo() {
        // this is straightforward but not really ideal
        // (IoCResolve is a holder for how I hit the container in global.asax)
        this.presenter = new FooPresenter(this, IoCResolve<IFooService>());

        // I would rather have an interface IFooPresenter so I can do
        this.presenter = IoCResolve<IFooPresenter>();
        // this allows me to add more services as needed without having to 
        // come back and manually update this constructor call here
    }
}

的问题是FooPresenter的构造预期特定页面，而不是容器创建一个新的。

The issue is FooPresenter's constructor expects the specific Page, not for the container to create a new one.

我可以提供的观点，当前页面的特定实例，到容器只是这一决议？这是否有意义的事，或者我应该这样做另一种方式？

Can I supply a specific instance of the view, the current page, to the container for just this resolution? Does that make sense to do, or should I do this another way?

推荐答案

要解决通过什么我喜欢叫的方式数据解决Autofac依赖参数时是使用的生成的工厂。

The way to solve passing what I like to call data parameters when resolving dependencies in Autofac is by using generated factories.

（更新：的这个问题讨论同样的问题，我的文章。展示了如何避免大量的工厂代表）

(Update: this question discusses the same problem and my article shows how you can avoid large amounts of factory delegates).

解决您的问题将是这个样子：

The solution to your problem will look something like this:

首先声明一个工厂委托thath 仅的接受数据参数：

First, declare a factory delegate thath only accepts the data parameters:

public delegate IFooPresenter FooPresenterFactory(IFooView view);

您演示云不变：

public FooPresenter : IFooPresenter {
    private IFooView view;
    private readonly IFooService service;

    public FooPresenter(IFooView view, IFooService service) {
        this.view = view;
        this.service = service;
    }
}

下一步Autofac容器的设置：

Next the Autofac container setup:

var builder = new ContainerBuilder();
builder.Register<FooService>().As<IFooService>().FactoryScoped();  
builder.Register<FooPresenter>().As<IFooPresenter>().FactoryScoped();  
builder.RegisterGeneratedFactory<FooPresenterFactory>();

现在在你的页面，您可以在两行代码解决演示首先，把工厂，然后调用工厂做的分辨率为您提供：

Now in your page you can in two lines of code resolve the presenter by first getting the factory and then calling the factory to do the resolution for you:

public partial class Foo : Page, IFooView {
    private FooPresenter presenter;

    public Foo() {
        var factory = IoCResolve<FooPresenterFactory>();
        this.presenter = factory(this);
    }
}

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