Add a sample for adding and configuring DI services together (#18429)

* dotnet new webapi

* Cleanup

* Basic sample

Author: serpent5

aspnetcore/fundamentals/configuration/options/samples/3.x/ServiceOptionsSample/Controllers/MyServiceController.cs

@@ -0,0 +1,20 @@
+using Microsoft.AspNetCore.Mvc;
+
+namespace ServiceOptionsSample.Controllers
+{
+    [ApiController]
+    [Route("api/MyService")]
+    public class MyServiceController : ControllerBase
+    {
+        private readonly IMyService myService;
+
+        public MyServiceController(IMyService myService)
+        {
+            this.myService = myService;
+        }
+
+        [HttpGet]
+        public IActionResult GetMyValue() =>
+            Ok(new { MyValue = myService.GetMyValue() });
+    }
+}

aspnetcore/fundamentals/configuration/options/samples/3.x/ServiceOptionsSample/MyService/IMyService.cs

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+namespace ServiceOptionsSample
+{
+    public interface IMyService
+    {
+        string GetMyValue();
+    }
+}

aspnetcore/fundamentals/configuration/options/samples/3.x/ServiceOptionsSample/MyService/MyService.cs

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+using Microsoft.Extensions.Options;
+
+namespace ServiceOptionsSample
+{
+    public class MyService : IMyService
+    {
+        private readonly MyServiceOptions myServiceOptions;
+
+        public MyService(IOptions<MyServiceOptions> myServiceOptionsAccessor)
+        {
+            myServiceOptions = myServiceOptionsAccessor.Value;
+        }
+
+        public string GetMyValue() =>
+            myServiceOptions.MyValue;
+    }
+}

aspnetcore/fundamentals/configuration/options/samples/3.x/ServiceOptionsSample/MyService/MyServiceOptions.cs

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+namespace ServiceOptionsSample
+{
+    public class MyServiceOptions
+    {
+        public string MyValue { get; set; } = "This is the default value";
+    }
+}

aspnetcore/fundamentals/configuration/options/samples/3.x/ServiceOptionsSample/MyService/MyServiceServiceCollectionExtensions.cs

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+using System;
+using Microsoft.Extensions.DependencyInjection.Extensions;
+using ServiceOptionsSample;
+
+namespace Microsoft.Extensions.DependencyInjection
+{
+    public static class MyServiceServiceCollectionExtensions
+    {
+        public static void AddMyService(this IServiceCollection services)
+        {
+            services.TryAddSingleton<IMyService, MyService>();
+        }
+
+        public static void AddMyService(this IServiceCollection services, Action<MyServiceOptions> setupAction)
+        {
+            services.AddMyService();
+            services.Configure(setupAction);
+        }
+    }
+}

aspnetcore/fundamentals/configuration/options/samples/3.x/ServiceOptionsSample/Program.cs

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+using Microsoft.AspNetCore.Hosting;
+using Microsoft.Extensions.Hosting;
+
+namespace ServiceOptionsSample
+{
+    public class Program
+    {
+        public static void Main(string[] args)
+        {
+            CreateHostBuilder(args).Build().Run();
+        }
+
+        public static IHostBuilder CreateHostBuilder(string[] args) =>
+            Host.CreateDefaultBuilder(args)
+                .ConfigureWebHostDefaults(webBuilder =>
+                {
+                    webBuilder.UseStartup<Startup>();
+                });
+    }
+}

aspnetcore/fundamentals/configuration/options/samples/3.x/ServiceOptionsSample/ServiceOptionsSample.csproj

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+<Project Sdk="Microsoft.NET.Sdk.Web">
+  <PropertyGroup>
+    <TargetFramework>netcoreapp3.1</TargetFramework>
+  </PropertyGroup>
+</Project>

aspnetcore/fundamentals/configuration/options/samples/3.x/ServiceOptionsSample/Startup.cs

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+using Microsoft.AspNetCore.Builder;
+using Microsoft.AspNetCore.Hosting;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Hosting;
+
+namespace ServiceOptionsSample
+{
+    public class Startup
+    {
+        public void ConfigureServices(IServiceCollection services)
+        {
+            services.AddMyService(options =>
+            {
+                options.MyValue = "This value was set in ConfigureServices";
+            });
+
+            services.AddControllers();
+        }
+
+        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
+        {
+            if (env.IsDevelopment())
+            {
+                app.UseDeveloperExceptionPage();
+            }
+
+            app.UseHttpsRedirection();
+
+            app.UseRouting();
+
+            app.UseEndpoints(endpoints =>
+            {
+                endpoints.MapControllers();
+            });
+        }
+    }
+}

aspnetcore/fundamentals/configuration/options/samples/3.x/ServiceOptionsSample/appsettings.json

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+{}