How do I access Configuration in any class in ASP.NET Core?

Question

I have gone through configuration documentation on ASP.NET core. Documentation says you can access configuration from anywhere in the application.

Below is Startup.c

Answer 1

I have to read own parameters by startup.
That has to be there before the WebHost is started (as I need the “to listen” url/IP and port from the parameter file and apply it to the WebHost). Further, I need the settings public in the whole application.

After searching for a while (no complete example found, only snippets) and after various try-and-error's, I have decided to do it the “old way" with an own .ini file.
So.. if you want to use your own .ini file and/or set the "to listen url/IP" your own and/or need the settings public, this is for you...

Complete example, valid for core 2.1 (mvc):

Create an .ini-file - example:

[Startup]
URL=http://172.16.1.201:22222
[Parameter]
*Dummy1=gew7623
Dummy1=true
Dummy2=1

whereby the Dummyx are only included as example for other date types than string (and also to test the case “wrong param” (see code below).

Added a code file in the root of the project, to store the global variables:

namespace MatrixGuide
{
    public static class GV
    {
        // In this class all gobals are defined

        static string _cURL;
        public static string cURL // URL (IP + Port) on that the application has to listen
        {
            get { return _cURL; }
            set { _cURL = value; }
        }

        static bool _bdummy1;
        public static bool bdummy1 // 
        {
            get { return _bdummy1; }
            set { _bdummy1 = value; }
        }

        static int _idummy1;
        public static int idummy1 // 
        {
            get { return _idummy1; }
            set { _idummy1 = value; }
        }

        static bool _bFehler_Ini;
        public static bool bFehler_Ini // 
        {
            get { return _bFehler_Ini; }
            set { _bFehler_Ini = value; }
        }

        // add further  GV variables here..
    }
    // Add further classes here... 
}

Changed the code in program.cs (before CreateWebHostBuilder()):

namespace MatrixGuide
{
    public class Program
    {
        public static void Main(string[] args)
        {
            // Read .ini file and overtake the contend in globale
            // Do it in an try-catch to be able to react to errors
            GV.bFehler_Ini = false;
            try
            {
                var iniconfig = new ConfigurationBuilder()
                .SetBasePath(Directory.GetCurrentDirectory())
                .AddIniFile("matrixGuide.ini", optional: false, reloadOnChange: true)
                .Build();
                string cURL = iniconfig.GetValue("Startup:URL");
                bool bdummy1 = iniconfig.GetValue("Parameter:Dummy1");
                int idummy2 = iniconfig.GetValue("Parameter:Dummy2");
                //
                GV.cURL = cURL;
                GV.bdummy1 = bdummy1;
                GV.idummy1 = idummy2;
            }
            catch (Exception e)
            {
                GV.bFehler_Ini = true;
                Console.ForegroundColor = ConsoleColor.Red;
                Console.WriteLine("!! Fehler beim Lesen von MatrixGuide.ini !!");
                Console.WriteLine("Message:" + e.Message);
                if (!(e.InnerException != null))
                {
                    Console.WriteLine("InnerException: " + e.InnerException.ToString());
                }

                Console.ForegroundColor = ConsoleColor.White;
            }
            // End .ini file processing
            //
            CreateWebHostBuilder(args).Build().Run();
        }

        public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
            WebHost.CreateDefaultBuilder(args)
            .UseStartup() //;
            .UseUrls(GV.cURL, "http://localhost:5000"); // set the to use URL from .ini -> no impact to IISExpress

    }
}

This way:

• My Application config is separated from the appsettings.json and I have no sideeffects to fear, if MS does changes in future versions ;-)
• I have my settings in global variables
• I am able to set the "to listen url" for each device, the applicaton run's on (my dev machine, the intranet server and the internet server)
• I'm able to deactivate settings, the old way (just set a * before)
• I'm able to react, if something is wrong in the .ini file (e.g. type mismatch)
  If - e.g. - a wrong type is set (e.g. the *Dummy1=gew7623 is activated instead of the Dummy1=true) the host shows red information's on the console (including the exception) and I' able to react also in the application (GV.bFehler_Ini ist set to true, if there are errors with the .ini)