c# - SimpleInjector 的 WebAPIRequest 生命周期是否包括消息处理程序？

Question

我是 SimpleInjector 的新手，正在研究将其与 WebAPI 结合使用的示例。我用了 SimpleInjector.Integration.WebApi.WebHost.QuickStart nu-get 包，然后为我的测试注册一个简单类型，如下所示:

container.RegisterWebApiRequest<SimplePOCO>();

从 ApiController 方法内部，我可以请求一个实例。到目前为止，一切都很好。我想将我的测试扩展到管道的早期，特别是消息处理程序。所以我创建了一个简单的 DelegatingHandler，例如:

protected override Task<HttpResponseMessage> SendAsync(
                                           HttpRequestMessage request,
                                           CancellationToken cancellationToken) {
    Task<HttpResponseMessage> response;

    var container =  SimpleInjectorWebApiInitializer.container;
    var rc = container.GetInstance<SimplePOCO>();
    response = base.SendAsync(request, cancellationToken);
    response.ContinueWith((responseMsg) =>  {   });

    return response;
}

调用 GetInstance<SimplePOCO>()错误并显示以下消息:

The registered delegate for type SimplePOCO threw an exception. The SimplePOCO is registered as 'Web API Request' lifestyle, but the instance is requested outside the context of a Web API Request.

我做错了什么吗？消息处理程序是否在 WebAPI 请求的生命周期之外？考虑到它们是多么完整，这似乎很奇怪。如果消息处理程序在生命周期之外，是否有更长的生命周期包含消息处理程序？

Answer 1

Are Message Handlers outside the lifetime of a WebAPI request?

嗯，事实上，他们是。除非您明确触发 IDependencyScope 的创建，否则会在 DefaultHttpControllerActivator 内部创建 IDependencyScope(通过调用 request.GetDependencyScope()) .Create 方法。

要确保您的代码在依赖范围内运行，您所要做的就是在您的处理程序中显式调用 request.GetDependencyScope():

protected override Task<HttpResponseMessage> SendAsync(
    HttpRequestMessage request, CancellationToken cancellationToken) {

    // trigger the creation of the scope.
    request.GetDependencyScope();

    Task<HttpResponseMessage> response;

    var container =  SimpleInjectorWebApiInitializer.container;
    var rc = container.GetInstance<SimplePOCO>();
    response = base.SendAsync(request, cancellationToken);
    response.ContinueWith((responseMsg) =>  {   });

    return response;
}