Passing IOptions into .Net core middleware class for json config retrieval

Few points:

• Constructor is missing in the mentioned class - MysettingsService
• Did you register the implementation of IMysettingsService in Startup class?
• While registering the implementation, you can initialize the MysettingsService, like below: services.AddSingleton<IMysettingsService, MysettingsService >(i => new MysettingsService ());

Follow these steps:

• Make sure that you have registered your JSON file - mysettings.json - in ConfigurationBuilder

• Define MySettings

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

• Define MySettingsService

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

• In Startup

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

EDITED -- I am including the implementation for you to follow

I have created a sample application and it works for me; Please follow the steps below:

Few details. My application name is: SettingsApp

1. Create the settings files - mySettings.json - with the contents

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

2. Configure it in the 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();}

See the line:

.AddJsonFile("mySettings.json", true, reloadOnChange: true)

3. Create MySettings object to hold the settings

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

Note: I use the namespace SettingsApp.Initialisations to keep this file. You can choose any based on your application structure.

4. Create the interface IMySettingsService

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

Note: I use the namespace SettingsApp.Services for this.

5. Implement the interface - 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;        }    }}

6. Add the options and let the system know your implementation in Startup.ConfigureServices method

// 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();}

Note to include the required using's.

Check the code below on how this is done:

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

7. Use the implementation (I am using the HomeController for testing.)

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();    }...

8. See the results:

In newer version of .NET above binding method does not work anymore.

I have created an extension method that works:

    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);    }

Use it like this:

services.AddSettings<LoggingSettings>(configuration);

Full example:

        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);