使用通用IHostBuilder时访问IServiceProvider [英] Access IServiceProvider when using generic IHostBuilder

问题描述

我在.NET Core 2.1控制台应用程序中使用 IHostBuilder 。 Main看起来像这样：

I'm using IHostBuilder in a .NET Core 2.1 console application. Main looks like this:

    public static async Task Main(string[] args)
    {
        var hostBuilder = new HostBuilder()
            .UseServiceProviderFactory(new AutofacServiceProviderFactory())
            .ConfigureServices(services =>
            {
                // Register dependencies
                // ...

                // Add the hosted service containing the application flow
                services.AddHostedService<RoomService>();
            });

        await hostBuilder.RunConsoleAsync();
    }
}

之前，使用 IWebHostBuilder ，我有 Configure（）方法可以让我做到这一点：

Before, with IWebHostBuilder, I had the Configure() method that let me do this:

public void Configure(IApplicationBuilder applicationBuilder, IHostingEnvironment environment)
{
    // Resolve something unrelated to the primary dependency graph
    var thingy = applicationBuilder.ApplicationServices.GetRequiredService<Thingy>();
    // Register it with the ambient context
    applicationBuilder.AddAmbientThingy(options => options.AddSubscriber(thingy));

    // Use MVC or whatever
    // ...
}

这使我可以注册一些周围环境的东西（使用环境上下文模式），而不是应用程序的主要依赖关系图的一部分。 （如您所见，我仍然使用容器来实例化它，这肯定比手动更新它更可取。我们可以将其视为辅助的，环境依赖性图。）

This allowed me to register something ambient (using the Ambient Context pattern), not part of the application's main dependency graph. (As you can see, I still use the container to instantiate it, which is certainly preferable to newing it up manually. We could see it as a secondary, ambient dependency graph.)

使用通用主机生成器，我们似乎永远无法访问已构建的 IServiceProvider 或 IApplicationBuilder 。在这种情况下，如何实现相同的注册？

With the generic host builder, we never seem to get access to the built IServiceProvider or the IApplicationBuilder. How do I achieve the same registration in this case?

推荐答案

显然，而不是调用 RunConsoleAsync（ ）扩展，我们可以拆分该方法执行的简单步骤，从而允许我们在构建和开始之间进行 的操作：

Apparently, instead of calling the RunConsoleAsync() extension, we can split up the simple steps that that method takes, allowing us to do something between building and starting:

        await hostBuilder
            .UseConsoleLifetime()
            .Build()
            .AddAmbientThingy(options => options.AddSubscriber(thingy))
            .RunAsync();

这篇关于使用通用IHostBuilder时访问IServiceProvider的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！