asp.net-core - 如何在 IHostingStartup 实现中访问配置？

Question

不支持尝试从 IHostingStartup 实现和构造函数注入(inject)中访问 IConfiguration。

正常的 Startup.cs 实现允许注入(inject) IConfiguration 使其易于从 ConfigureService() 和 中访问Configure() 方法。

获取配置访问权限的最佳实践方法是什么？

Answer 1

某些构建器方法(即 ConfigureLogging() ConfigureAppConfiguration() ConfigureServices() 允许 WebHostBuilderContext 重载传递到操作中。

WebHostBuilderContext提供对托管环境和配置的访问

    public class HostingStartupConfiguration : IHostingStartup
    {
        public void Configure(IWebHostBuilder builder)
        {
            builder
                .ConfigureLogging((context, builder) =>
                {
                    // clear providers set from host application
                    if (context.HostingEnvironment.IsDevelopment())
                    {
                        ...
                    }
                })
                .ConfigureAppConfiguration((context, builder) =>
                {
                    if (context.HostingEnvironment.IsDevelopment())
                        Console.WriteLine("we are in dev mode");

                    ...
                })
                .ConfigureServices((context, services) =>
                {
                    ...

                    // get assemblies based on configuration to load as Application Parts
                    var assemblies = GetControllerAssemblies(context.Configuration);

                    // register controllers application parts from external assemblies
                    foreach (var assembly in assemblies)
                    {
                        builder.AddApplicationPart(assembly);
                    }

                    ...
                });
        }