unable to inject dependency in .net core 3.1

Question

Hi i am following microsoft docs ...

https://docs.microsoft.com/en-us/aspnet/core/fundamentals/configuration/?view=aspnetcore-3.1#json-configuration-provider

in order to inject configurations as singleton in .NET Core Web API

Here is Program.cs code where i load my configurations:

public class Program
{
    public static Dictionary<string, string> arrayDict =
   new Dictionary<string, string>
   {
        {"connString", "Data Source =xxx/xxx;User Id =xxx;Password =xxx"}
   };
    public static void Main(string[] args)
    {
        CreateHostBuilder(args).Build().Run();
    }

    public static IHostBuilder CreateHostBuilder(string[] args) =>
        Host.CreateDefaultBuilder(args)
        .ConfigureAppConfiguration(builder =>
        {
            builder.AddInMemoryCollection(arrayDict);
            builder.AddJsonFile(
                "appsettings.json", optional: false, reloadOnChange: false);
        })
        .ConfigureWebHostDefaults(webBuilder =>
        {
            webBuilder.UseStartup<Startup>();
        });
}

Here in Startup.cs i use following

public class Startup
{
    private readonly IConfiguration Configuration;

    public Startup(IConfiguration config)
    {
        Configuration = config;
    }


    // This method gets called by the runtime. Use this method to add services to the container.
    public void ConfigureServices(IServiceCollection services)
    {
        services.AddControllers();
        services.AddSingleton<IConfiguration>(Configuration);
    }

    // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
    public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
    {
        if (env.IsDevelopment())
        {
            app.UseDeveloperExceptionPage();
        }

        app.UseHttpsRedirection();

        app.UseRouting();

        app.UseAuthorization();

        app.UseEndpoints(endpoints =>
        {
            endpoints.MapControllers();
        });
    }
}

Still when i am using dependency injection in my Controller i am unable to inject IConfiguration, and get following error at invoking cotroller action (runtime error):

A suitable constructor for type 'IrisDotNetCore.Controllers.LoginController' could not be located. Ensure the type is concrete and services are registered for all parameters of a public constructor.

LoginController.cs Code:

[Route("api/[controller]")]
[ApiController]
public class LoginController : ControllerBase
{
    IConfiguration _configuration;


    LoginController(IConfiguration configuration)
    {
        _configuration = configuration;
    }
}

What is possibly wrong here?

This might be an XY problem. Why arre you trying to inject IConfiguration to begin with. That can be seen as a code smell. — Nkosi

Tearth Tearth · Accepted Answer · 2020-02-20T13:47:10

Your constructor has to be public or internal - remember that in your situation the instance of the LoginController can't be created (because LoginController method is private). Even the error message (Ensure the type is concrete and services are registered for all parameters of a public constructor) suggests this.

unable to inject dependency in .net core 3.1

1 Answers