Question

我正在尝试根据.net核心中的Options pattern使用强类型json配置设置。到目前为止，所有示例都显示了将强类型设置类注入控制器是多么容易，但是我需要在中间件类中使用它（非常类似于this question但是在尝试之后我没有进一步前进）。

所以，设置：

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; 
    }
}

如何实例化 MysettingsService.cs 并在类构造函数中注入IOptions<MySettings>以便我可以调用 GetName 方法？

Answer 1

几点：

上述课程中缺少构造函数 - MysettingsService
您是否在启动课程中注册了 IMysettingsService 的实施？
在注册实施时，您可以初始化 MysettingsService ，如下所示： services.AddSingleton<IMysettingsService, MysettingsService >(i => new MysettingsService ());

请按照以下步骤操作：

确保您已在ConfigurationBuilder

定义 MySettings

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

    public string Description { get; set; }
}

定义 MySettingsService

public class MySettingsService : IMySettingsService
{
    private readonly MySettings mySettings;

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

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

在初创公司

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

已编辑 - 我已将您的实施内容包括在内

我已经创建了一个示例应用程序，它对我有用;请按照以下步骤操作：

几个细节。我的申请名称是：SettingsApp

使用内容

mySettings.json

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

在Startup

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();
}

见行：

.AddJsonFile（“mySettings.json”，true，reloadOnChange：true）

创建MySettings对象以保存设置

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

        public string Description { get; set; }
    }
}

注意：我使用命名空间SettingsApp.Initialisations来保留此文件。您可以根据应用程序结构选择任何一种。

创建界面IMySettingsService

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

注意：我使用命名空间SettingsApp.Services。

实施界面 - 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;
        }
    }
}

添加选项，让系统了解您在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();
}

请注意包含所需的使用。

检查以下代码如何完成：

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

使用实现（我使用HomeController进行测试。）

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();
    }

...

查看结果：

Answer 2

在较新版本的.NET中，上面的绑定方法不再起作用了。

我创建了一个有效的扩展方法：

    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);
    }

像这样使用：

services.AddSettings<LoggingSettings>(configuration);

完整示例：

        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);

将IOptions传递到.Net核心中间件类以进行json配置检索

2 个答案: