Dependency Injection not working for IConfiguration C#.Net Core

Question

I have injected IConfiguration using following code:

 public class InjectorConfig
    {
        /// <summary>
        /// configuration for DI
        /// </summary>
        /// <param name="services"></param>
        /// <param name="configuration"></param>
        public static void Init(IServiceCollection services, IConfiguration configuration)
        {
            services.AddSingleton<IConfiguration>(provider => configuration);
            services.AddSingleton<AppSettingUtil>();
        }
}

while using this in my class called AppSettingUtil I am getting null pointer exception on IConfiguration object.

Below is the code I am using

public class AppSettingUtil
    {     
       public AppSettingUtil(IConfiguration configuration)
       {
          _configuration = configuration;
       }
       public IConfiguration Configuration { get; }
    }

While executing below function I am getting null pointer exception

 private static object GetDefault(string name)
    {
        if (_configuration[name] != null)
        {
            return Convert.ToInt32(_configuration[name]);
        }
        return null;
    }

While executing this function the object _configuration is null, and hence throwing null pointer exception,

Please show us an [MCVE](https://stackoverflow.com/help/mcve). — Steven, Apr 22 '19 at 11:14
Have you set a breakpoint to confirm that your `Init` method is actually getting called? — Scott Hannen, Apr 22 '19 at 12:27
I got the issue, it was just a silly mistake, Method getDefault() is a static method and I am calling it by using class name(ie. without creating object) hence the constructor is not getting executed and _configuration is not getting initialized, Thanks for the support — SwapnilKumbhar, Apr 23 '19 at 15:55
Does this answer your question? [How to get an instance of IConfiguration in asp.net core?](https://stackoverflow.com/questions/48017390/how-to-get-an-instance-of-iconfiguration-in-asp-net-core) — Ian Kemp, Dec 24 '20 at 10:04
Check this out for .NET 6: https://stackoverflow.com/q/76909010/8644294 — Ash K, Aug 16 '23 at 14:49

score 21 · Accepted Answer · edited Sep 16 '22 at 15:38

I use this one in ASP.Net Core and works it for me:

public class Startup
{
    public Startup(IHostingEnvironment env , IConfiguration configuration)
    {
        Configuration = configuration;
    }

    public IConfiguration Configuration { get; }

    public void ConfigureServices(IServiceCollection services)
    {
        services.AddSingleton<IConfiguration>(provider => configuration);
        services.AddSingleton<AppSettingUtil>();
    }
}

score 6 · Answer 2 · answered Jan 07 '20 at 15:49

It also can be done as follows:

(I did this in the main thread of a .net core console app)

public static void Main(string[] args)
        {

            IConfigurationBuilder configurationBuilder = new ConfigurationBuilder();
            // Duplicate here any configuration sources you use.
            configurationBuilder.AddJsonFile("AppSettings.json");
            IConfiguration configuration = configurationBuilder.Build();

            Program.token = configuration["token"];
            Program.guidID = configuration["guidID"];
            Program.kind = configuration["kind"];

I found the solution in this stackoverflow question.

It works for me. Hope it works for you too.

Dependency Injection not working for IConfiguration C#.Net Core

2 Answers2

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