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 cs created by template  public class Startup       public Startup IHostingEnvironment env                var builder   new ConfigurationBuilder                SetBasePath env ContentRootPath               AddJsonFile  appsettings json   optional  true  reloadOnChange  true               AddJsonFile   appsettings  env EnvironmentName  json   optional  true            if  env IsEnvironment  Development                             This will push telemetry data through Application Insights pipeline faster  allowing you to view results immediately              builder AddApplicationInsightsSettings developerMode  true                      builder AddEnvironmentVariables            Configuration   builder Build               public IConfigurationRoot Configuration   get            This method gets called by the runtime  Use this method to add services to the container     public void ConfigureServices IServiceCollection services                   Add framework services          services AddApplicationInsightsTelemetry Configuration            services AddMvc                  This method gets called by the runtime  Use this method to configure the HTTP request pipeline     public void Configure IApplicationBuilder app  IHostingEnvironment env  ILoggerFactory loggerFactory                loggerFactory AddConsole Configuration GetSection  Logging             loggerFactory AddDebug             app UseApplicationInsightsRequestTelemetry             app UseApplicationInsightsExceptionTelemetry             app UseMvc              So in Startup cs we configure all the settings  Startup cs also has a property named Configuration  What I m not able to understand how do you access this configuration in controller or anywhere in the application  MS is recommending to use options pattern but I have only 4-5 key-value pairs so I would like not to use options pattern  I just wanted to have access to Configuration in application  How do I inject it in any class

User · Answer

In ASP NET Core  there are configuration providers for reading configurations from almost anywhere such as files e g  JSON  INI or XML  environment variables  Azure key vault  command-line arguments  etc  and many more sources  I have written a step by step guide to show you how can you configure your application settings in various files such as JSON  INI or XML and how can you read those settings from your application code  I will also demonstrate how can you read application settings as custom  NET types  classes  and how can you use the built-in ASP NET Core dependency injection to read your configuration settings in multiple classes  services or even projects available in your solution  Read A Step by Step Guide for ASP NET Core Configuration

User · Answer

I looked into the options pattern sample and saw this   public class Startup       public Startup IConfiguration config                   Configuration from appsettings json has already been loaded by            CreateDefaultBuilder on WebHost in Program cs  Use DI to load            the configuration into the Configuration property          Configuration   config                When adding Iconfiguration in the constructor of my class  I could access the configuration options through DI   Example   public class MyClass       private Iconfiguration  config       public MyClass Iconfiguration config            config   config                    access  config  myAppSetting   anywhere in this class

User · Answer

I m doing it like this at the moment      Requires NuGet package Microsoft Extensions Configuration Json  using Microsoft Extensions Configuration  using System IO   namespace ImagesToMssql AppsettingsJson       public static class AppSettingsJson                          public static IConfigurationRoot GetAppSettings                         string applicationExeDirectory   ApplicationExeDirectory                 var builder   new ConfigurationBuilder                SetBasePath applicationExeDirectory               AddJsonFile  appsettings json                 return builder Build                       private static string ApplicationExeDirectory                         var location   System Reflection Assembly GetExecutingAssembly   Location              var appRoot   Path GetDirectoryName location                return appRoot                      And then I use this where I need to get the data from the appsettings json file   var appSettingsJson   AppSettingsJson GetAppSettings       appSettingsJson  keyName

User · Answer

In 8-2017 Microsoft came out with System Configuration for  NET CORE v4 4  Currently v4 5 and v4 6 preview   For those of us  who works on transformation from  Net Framework to CORE  this is essential  It allows to keep and use current app config files  which can be accessed from any assembly  It is probably even can be an alternative to appsettings json  since Microsoft realized the need for it  It works same as before in FW  There is one difference   In the web applications   e g  ASP NET CORE WEB API  you need to use app config and not web config for your appSettings or configurationSection  You might need to use web config but only if you deploying your site via IIS  You place IIS-specific settings into web config  I ve tested it with netstandard20 DLL and Asp net Core Web Api and it is all working

User · Answer

I know this is old but given the IOptions patterns is relatively simple to implement    Class with public get set properties that match the settings in the configuration  public class ApplicationSettings       public string UrlBasePath   get  set       register your settings   public void ConfigureServices IServiceCollection services          services Configure lt ApplicationSettings gt  Configuration GetSection  ApplicationSettings            inject via IOptions  public class HomeController      public HomeController IOptions lt ApplicationSettings gt  appSettings               appSettings Value UrlBasePath                or better practice create a readonly private reference             I m not sure why you wouldn t just do this

User · Answer

Using the Options pattern in ASP NET Core is the way to go  I just want to add  if you need to access the options within your startup cs  I recommend to do it this way   CosmosDbOptions cs    public class CosmosDbOptions       public string ConnectionString   get  set        Startup cs   public void ConfigureServices IServiceCollection services           This is how you can access the Connection String      var connectionString   Configuration GetSection nameof CosmosDbOptions   nameof CosmosDbOptions ConnectionString

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I know there may be several ways to do this  I m using Core 3 1 and was looking for the optimal cleaner option and I ended up doing this    My startup class is as default   public Startup IConfiguration configuration        Configuration   configuration     public IConfiguration Configuration   get        This method gets called by the runtime  Use this method to add services to the container  public void ConfigureServices IServiceCollection services        services AddControllers         My appsettings json is like this        CompanySettings          name    Fake Co            My class is an API Controller  so first I added the using reference and then injected the IConfiguration interface   using Microsoft Extensions Configuration   public class EmployeeController        private IConfiguration  configuration      public EmployeeController IConfiguration configuration                 configuration   configuration             Finally I used the GetValue method   public async Task lt IActionResult gt  Post  FromBody  EmployeeModel form        var companyName   configuration GetValue lt string gt   CompanySettings name           companyName    Fake Co

User · Answer

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 lt string gt   Startup URL                    bool bdummy1   iniconfig GetValue lt bool gt   Parameter Dummy1                    int idummy2   iniconfig GetValue lt int gt   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    gt              WebHost CreateDefaultBuilder args               UseStartup lt Startup gt                     UseUrls GV cURL   http   localhost 5000       set the to use URL from  ini - gt  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

User · Answer

Update  Using ASP NET Core 2 0 will automatically add the IConfiguration instance of your application in the dependency injection container  This also works in conjunction with ConfigureAppConfiguration on the WebHostBuilder   For example   public static void Main string   args        var host   WebHost CreateDefaultBuilder args           ConfigureAppConfiguration builder   gt                        builder AddIniFile  foo ini                        UseStartup lt Startup gt             Build         host Run          It s just as easy as adding the IConfiguration instance to the service collection as a singleton object in ConfigureServices   public void ConfigureServices IServiceCollection services       services AddSingleton lt IConfiguration gt  Configuration                  Where Configuration is the instance in your Startup class   This allows you to inject IConfiguration in any controller or service   public class HomeController      public HomeController IConfiguration configuration                Use IConfiguration instance

User · Answer

There is also an option to make configuration static in startup cs so that what you can access it anywhere with ease  static variables are convenient huh    public Startup IConfiguration configuration        Configuration   configuration     internal static IConfiguration Configuration   get  private set      This makes configuration accessible anywhere using Startup Configuration GetSection    What can go wrong

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The right way to do it    In  NET Core you can inject the IConfiguration as a parameter into your Class constructor  and it will be available   public class MyClass        private IConfiguration configuration      public MyClass IConfiguration configuration                ConnectionString   new configuration GetValue lt string gt   ConnectionString            Now  when you want to create an instance of your class  since your class gets injected the IConfiguration  you won t be able to just do new MyClass    because it needs a IConfiguration parameter injected into the constructor  so  you will need to inject your class as well to the injecting chain  which means two simple steps    1  Add your Class es - where you want to use the IConfiguration  to the IServiceCollection at the ConfigureServices   method in Startup cs  services AddTransient lt MyClass gt       2  Define an instance - let s say in the Controller  and inject it using the constructor   public class MyController   ControllerBase       private MyClass  myClass      public MyController MyClass myClass                 myClass   myClass          Now you should be able to enjoy your  myClass configuration freely        Another option    If you are still looking for a way to have it available without having to inject the classes into the controller  then you can store it in a static class  which you will configure in the Startup cs  something like   public static class MyAppData       public static IConfiguration Configuration      And your Startup constructor should look like this   public Startup IConfiguration configuration        Configuration   configuration      MyAppData Configuration   configuration      Then use MyAppData Configuration anywhere in your program   Don t confront me why the first option is the right way  I can just see experienced developers always avoid garbage data along their way  and it s well understood that it s not the best practice to have loads of data available in memory all the time  neither is it good for performance and nor for development  and perhaps it s also more secure to only have with you what you need

[c#] How do I access Configuration in any class in ASP.NET Core?

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