將IOptions傳遞到.Net核心中間件類用於json配置檢索

Question

我試圖使用.net核心中的Options pattern強類型json配置設置。到目前爲止，所有示例都顯示了將強類型設置類注入控制器是多麼容易，但我需要在中間件類中使用它（非常類似於this question，但在嘗試這種方法後我沒有進一步前瞻）。

因此，設置：

mysettings.json

{ 
    "MySettings": { 
    "Name": "Some Name from config", 
    "Description": "Some Description from config" 
    } 
} 

mysettings.cs

public class MySettings 
    { 
     public string Name { get; set; } = "Default name"; 

     public string Description { get; set; } = "Default description"; 
    } 

startup.cs

 public void ConfigureServices(IServiceCollection services) 
      { 
       services.AddMvc(); 

       // Add functionality to inject IOptions<T> 
       services.AddOptions(); 

       // Add our Config object so it can be injected 
       services.Configure<MySettings>(Configuration.GetSection("MySettings")); 
       services.AddSingleton<IMySettingsService, MySettingsService>(); 
      } 

MysettingsService.cs

 public class MysettingsService : IMysettingsService 
      { 
       private MySettings mySettings { get; set; } 

       public MysettingsService (MySettings _mySettings) 
       { 
        mySettings = _mySettings.value; 
       } 


     public string GetName() 
       { 
        return mySettings.Name; 
       } 
    } 

如何去實例MysettingsService.cs和注入IOptions<MySettings>到類的構造函數，所以我可以調用的GetName方法？

Answer 1

幾點：

• 構造函數中缺少提到的類 - MysettingsService
• 你已經註冊IMysettingsService的實施啓動類？
• 雖然註冊的實施，可以初始化MysettingsService，如下圖所示： services.AddSingleton<IMysettingsService, MysettingsService >(i => new MysettingsService());

遵循以下步驟：

• 確保您已註冊的JSON文件 - mysettings。JSON - 在ConfigurationBuilder

• 定義MySettings

  public class MySettings 
  { 
      public string Name { get; set; } 
  
      public string Description { get; set; } 
  } 
  

• 定義MySettingsService

  public class MySettingsService : IMySettingsService 
  { 
      private readonly MySettings mySettings; 
  
      public MySettingsService (IOptions<MySettings> _mySettings) 
      { 
       mySettings = _mySettings.Value; 
      } 
  
      public string GetName() 
      { 
       return mySettings.Name; 
      } 
  } 
  

• 在啓動

  services.Configure<MySettings>(this.Configuration.GetSection("MySettings")); 
  services.AddSingleton<IMySettingsService, MySettingsService >(); 
  

編輯 - 我包括執行你跟着

我創建了一個示例應用程序，它爲我的作品;請按照以下步驟操作：

幾個細節。 我的應用程序名是：SettingsApp

1. 創建設置文件 - mySettings.json - 與內容

{ 
    "MySettings": { 
    "Name": "Some Name from config", 
    "Description": "Some Description from config" 
    } 
} 

在Startup配置它

public Startup(IHostingEnvironment env) 
{ 
    var builder = new ConfigurationBuilder() 
     .SetBasePath(env.ContentRootPath) 
     .AddJsonFile("mySettings.json", true, reloadOnChange: true) 
     .AddJsonFile("appsettings.json", optional: true, reloadOnChange: true) 
     .AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true) 
     .AddEnvironmentVariables(); 

    if (env.IsDevelopment()) 
    { 
     // This will push telemetry data through Application Insights pipeline faster, allowing you to view results immediately. 
     builder.AddApplicationInsightsSettings(developerMode: true); 
    } 
    Configuration = builder.Build(); 
} 

見線：

.AddJsonFile（ 「mySettings.json」，真，reloadOnChange：真）

創建MySettings對象保持設置

namespace SettingsApp.Initialisations 
{ 
    public class MySettings 
    { 
     public string Name { get; set; } 

     public string Description { get; set; } 
    } 
} 

說明：我使用命名空間SettingsApp.Initialisations來保留此文件。您可以根據您的應用程序結構選擇任何一種。

創建接口IMySettingsService

namespace SettingsApp.Services 
{ 
    public interface IMySettingsService 
    { 
     string GetName(); 
    } 
} 

注：我使用的命名空間SettingsApp.Services此。

實現接口 - IMySettingsService

using SettingsApp.Initialisations; 
using Microsoft.Extensions.Options; 

namespace SettingsApp.Services 
{ 
    public class MySettingsService : IMySettingsService 
    { 
     private readonly MySettings mySettings; 

     public MySettingsService(IOptions<MySettings> _mySettings) 
     { 
      mySettings = _mySettings.Value; 
     } 

     public string GetName() 
     { 
      return mySettings.Name; 
     } 
    } 
} 

添加的選項，讓系統知道你的實現在Startup.ConfigureServices方法

// This method gets called by the run time. Use this method to add services to the container. 
public void ConfigureServices(IServiceCollection services) 
{ 
    // Options 
    services.AddOptions(); 
    services.Configure<MySettings>(this.Configuration.GetSection("MySettings")); 
    services.AddSingleton<IMySettingsService, MySettingsService>(); 

    // Add framework services. 
    services.AddApplicationInsightsTelemetry(Configuration); 

    services.AddMvc(); 
} 

請注意包括所需使用的。

檢查如何做到這一點下面的代碼：

// Options 
services.AddOptions(); 
services.Configure<MySettings>(this.Configuration.GetSection("MySettings")); 
services.AddSingleton<IMySettingsService, MySettingsService>(); 

使用實施（我用的是HomeController進行測試。）

public class HomeController : Controller 
{ 
    private IMySettingsService mySettingsService; 

    public HomeController(IMySettingsService settingsService) 
    { 
     mySettingsService = settingsService; 
    } 

    public IActionResult Index() 
    { 
     // Get the settings 
     var name = mySettingsService.GetName(); 

     return View(); 
    } 

... 

查看結果：

Answer 2

在.NET的較新版本的上述結合方法不工作了。

我已經創建了一個擴展方法的工作原理：

public static void AddSettings<T>(this IServiceCollection serviceCollection, IConfiguration configuration) where T : class, new() 
    { 
     var settings = new T(); 
     configuration.Bind(typeof(T).Name, settings); 
     serviceCollection.AddSingleton(settings); 
    } 

使用方法如下：

 string pathToConfigFile = "c:\\config.json"; 
     IConfiguration configuration = new ConfigurationBuilder() 
      .AddJsonFile(pathToConfigFile, optional: false, reloadOnChange: true) 
      .Build(); 

     var services = new ServiceCollection() 

     services.AddSingleton(configuration); 

     services.AddSettings<ConnectionSettings>(configuration); 
     services.AddSettings<LoggingSettings>(configuration); 
     services.AddSettings<AutoCreateSettings>(configuration);