Getting value from appsettings json in net core

Question

Not sure what am I missing here but I am not able to get the values from my appsettings json in my  net core application  I have my appsettings json as          AppSettings              Version    One            Startup   public class Startup       private IConfigurationRoot  configuration      public Startup IHostingEnvironment env                 configuration   new ConfigurationBuilder             public void ConfigureServices IServiceCollection services                Here I setup to read appsettings               services Configure lt AppSettings gt   configuration GetSection  AppSettings               Model   public class AppSettings       public string Version  get  set        Controller   public class HomeController   Controller       private readonly AppSettings  mySettings       public HomeController IOptions lt AppSettings gt  settings                  This is always null          mySettings   settings Value             mySettings is always null  Is there something that I am missing here

User · Answer

This tends to happen particularly with vscode as I'd assume because of how one configures the launch.json.

Based on this answer I had to reconfigure the base path the configuration is being searched for to that of DLL's path, and since the default setting was optional it was hard to track this down on a .net core 3.1 & net 5.0 app. Here's how I've reconfigured

Program.cs:

using System;
using System.IO;
using System.Reflection;
using Microsoft.Extensions.Configuration;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Hosting;

namespace API
{
    public class Program
    {
        public static int Main(string[] args)
        {
            CreateHostBuilder(args).Build().Run();
            return 0;
        }

        public static IHostBuilder CreateHostBuilder(string[] args)
        {
            return Host.CreateDefaultBuilder(args)
            .ConfigureAppConfiguration(c =>
            {
                var codeBase = Assembly.GetExecutingAssembly().Location;
                var uri = new UriBuilder(codeBase);
                var path = Uri.UnescapeDataString(uri.Path);
                var assembyDirectory = Path.GetDirectoryName(path);
                c.SetBasePath(assembyDirectory);
            })
            .ConfigureWebHostDefaults(webBuilder =>
            {
                webBuilder.UseStartup<Startup>();
            })
            ;
        }
    }
}

I could access the configuration fine in Startup.cs:

using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Model;

namespace API
{
    public class Startup
    {
        public IConfiguration Configuration { get; }

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

        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {
            var myOptions = Configuration.To<ApiConfig>();
            services.AddAuthentication(myOptions.Secret);
            services.AddControllers();
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            app.UseRouting();
            app.UseAuthentication();
            app.UseAuthorization();
            app.UseEndpoints(endpoints => { endpoints.MapControllers(); });
        }
    }
}

User · Answer

Program and Startup class  NET Core 2 x You don t need to new IConfiguration in the Startup constructor  Its implementation will be injected by the DI system     Program cs public class Program       public static void Main string   args                BuildWebHost args  Run               public static IWebHost BuildWebHost string   args    gt          WebHost CreateDefaultBuilder args               UseStartup lt Startup gt                 Build                      Startup cs public class Startup       public IHostingEnvironment HostingEnvironment   get  private set        public IConfiguration Configuration   get  private set         public Startup IConfiguration configuration  IHostingEnvironment env                this HostingEnvironment   env          this Configuration   configuration            NET Core 1 x You need to tell Startup to load the appsettings files     Program cs public class Program       public static void Main string   args                var host   new WebHostBuilder                UseKestrel                UseContentRoot Directory GetCurrentDirectory                 UseIISIntegration                UseStartup lt Startup gt                 UseApplicationInsights                Build             host Run               Startup cs public class Startup       public IConfigurationRoot Configuration   get  private set         public Startup IHostingEnvironment env                var builder   new ConfigurationBuilder                SetBasePath env ContentRootPath               AddJsonFile  quot appsettings json quot   optional  false  reloadOnChange  true               AddJsonFile   quot appsettings  env EnvironmentName  json quot   optional  true               AddEnvironmentVariables             this Configuration   builder Build                      Getting Values There are many ways you can get the value you configure from the app settings   Simple way using ConfigurationBuilder GetValue lt T gt  Using Options Pattern  Let s say your appsettings json looks like this         quot ConnectionStrings quot                             quot AppIdentitySettings quot              quot User quot                  quot RequireUniqueEmail quot   true                     quot Password quot                  quot RequiredLength quot   6               quot RequireLowercase quot   true               quot RequireUppercase quot   true               quot RequireDigit quot   true               quot RequireNonAlphanumeric quot   true                     quot Lockout quot                  quot AllowedForNewUsers quot   true               quot DefaultLockoutTimeSpanInMins quot   30               quot MaxFailedAccessAttempts quot   5                       quot Recaptcha quot                                    Simple Way You can inject the whole configuration into the constructor of your controller class  via IConfiguration  and get the value you want with a specified key  public class AccountController   Controller       private readonly IConfiguration  config       public AccountController IConfiguration config                 config   config              AllowAnonymous      public IActionResult ResetPassword int userId  string code                var vm   new ResetPasswordViewModel                       PasswordRequiredLength    config GetValue lt int gt                    quot AppIdentitySettings Password RequiredLength quot                RequireUppercase    config GetValue lt bool gt                    quot AppIdentitySettings Password RequireUppercase quot                       return View vm            Options Pattern The ConfigurationBuilder GetValue lt T gt  works great if you only need one or two values from the app settings  But if you want to get multiple values from the app settings  or you don t want to hard code those key strings in multiple places  it might be easier to use Options Pattern  The options pattern uses classes to represent the hierarchy structure  To use options pattern   Define classes to represent the structure Register the configuration instance which those classes bind against Inject IOptions lt T gt  into the constructor of the controller class you want to get values on  1  Define configuration classes to represent the structure You can define classes with properties that need to exactly match the keys in your app settings  The name of the class does t have to match the name of the section in the app settings  public class AppIdentitySettings       public UserSettings User   get  set        public PasswordSettings Password   get  set        public LockoutSettings Lockout   get  set       public class UserSettings       public bool RequireUniqueEmail   get  set       public class PasswordSettings       public int RequiredLength   get  set        public bool RequireLowercase   get  set        public bool RequireUppercase   get  set        public bool RequireDigit   get  set        public bool RequireNonAlphanumeric   get  set       public class LockoutSettings       public bool AllowedForNewUsers   get  set        public int DefaultLockoutTimeSpanInMins   get  set        public int MaxFailedAccessAttempts   get  set       2  Register the configuration instance And then you need to register this configuration instance in ConfigureServices   in the start up  using Microsoft Extensions Configuration  using Microsoft Extensions DependencyInjection       namespace DL SO UI Web       public class Startup                           public void ConfigureServices IServiceCollection services                                        var identitySettingsSection                     configuration GetSection  quot AppIdentitySettings quot                services Configure lt AppIdentitySettings gt  identitySettingsSection                                                  3  Inject IOptions Lastly on the controller class you want to get the values  you need to inject IOptions lt AppIdentitySettings gt  through constructor  public class AccountController   Controller       private readonly AppIdentitySettings  appIdentitySettings       public AccountController IOptions lt AppIdentitySettings gt  appIdentitySettingsAccessor                 appIdentitySettings   appIdentitySettingsAccessor Value              AllowAnonymous      public IActionResult ResetPassword int userId  string code                var vm   new ResetPasswordViewModel                       PasswordRequiredLength    appIdentitySettings Password RequiredLength              RequireUppercase    appIdentitySettings Password RequireUppercase                     return View vm

User · Answer

I think the best option is    Create a model class as config schema Register in DI  services Configure Configuration GetSection  democonfig     Get the values as model object from DI in your controller   private readonly your model myConfig  public DemoController IOptions lt your model gt  configOps        this myConfig   configOps Value

User · Answer

In my case it was simple as using the Bind   method on the Configuration object  And then add the object as singleton in the DI   var instructionSettings   new InstructionSettings    Configuration Bind  InstructionSettings   instructionSettings   services AddSingleton typeof IInstructionSettings    serviceProvider    gt  instructionSettings     The Instruction object can be as complex as you want         InstructionSettings          Header    uat TEST        SVSCode    FICA        CallBackUrl    https   UATEnviro companyName co za suite webapi receiveCallback        Username    s integrat        Password    X nkmail6        Defaults          Language    ENG        ContactDetails            StreetNumber    9           StreetName    Nano Drive           City    Johannesburg           Suburb    Sandton           Province    Gauteng           PostCode    2196           Email    ourDefaultEmail companyName co za           CellNumber    0833 468 378           HomeNumber    0833 468 378                  CountryOfBirth    710

User · Answer

For ASP NET Core 3 1 you can follow this guide   https   docs microsoft com en-us aspnet core fundamentals configuration  view aspnetcore-3 1  When you create a new ASP NET Core 3 1 project you will have the following configuration line in Program cs   Host CreateDefaultBuilder args    This enables the following    ChainedConfigurationProvider   Adds an existing IConfiguration as a source  In the default configuration case  adds the host configuration and setting it as the first source for the app configuration   appsettings json using the JSON configuration provider   appsettings Environment json using the JSON configuration provider  For example  appsettings Production json and appsettings Development json   App secrets when the app runs in the Development environment   Environment variables using the Environment Variables configuration provider   Command-line arguments using the Command-line configuration provider    This means you can inject IConfiguration and fetch values with a string key  even nested values  Like IConfiguration  Parent Child     Example   appsettings json       ApplicationInsights                  Instrumentationkey   putrealikeyhere            WeatherForecast cs   ApiController   Route   controller     public class WeatherForecastController   ControllerBase       private static readonly string   Summaries   new                  Freezing    Bracing    Chilly    Cool    Mild    Warm    Balmy    Hot    Sweltering    Scorching              private readonly ILogger lt WeatherForecastController gt   logger      private readonly IConfiguration  configuration       public WeatherForecastController ILogger lt WeatherForecastController gt  logger  IConfiguration configuration                 logger   logger           configuration   configuration              HttpGet      public IEnumerable lt WeatherForecast gt  Get                 var key    configuration  ApplicationInsights InstrumentationKey             var rng   new Random            return Enumerable Range 1  5  Select index   gt  new WeatherForecast                       Date   DateTime Now AddDays index               TemperatureC   rng Next -20  55               Summary   Summaries rng Next Summaries Length                       ToArray

User · Answer

In the constructor of Startup class  you can access appsettings json and many other settings using the injected IConfiguration object   Startup cs Constructor      public Startup IConfiguration configuration                Configuration   configuration             here you go         var myvalue   Configuration  Grandfather Father Child            public IConfiguration Configuration   get      Contents of appsettings json         Grandfather          Father            Child    myvalue

User · Answer

Adding to David Liang s answer for Core 2 0 -   appsettings json file s are linked to ASPNETCORE ENVIRONMENT variable   ASPNETCORE ENVIRONMENT can be set to any value  but three values are supported by the framework  Development  Staging  and Production  If ASPNETCORE ENVIRONMENT isn t set  it will default to Production   For these three values these appsettings ASPNETCORE ENVIRONMENT json files are supported out of the box - appsettings Staging json  appsettings Development json and appsettings Production json  The above three application setting json files can be used to configure multiple environments   Example - appsettings Staging json            Logging              IncludeScopes   false           LogLevel                  System    Information                Microsoft    Information                        MyConfig    My Config Value for staging       Use Configuration  config var   to retrieve any configuration value     public class Startup       public Startup IHostingEnvironment env  IConfiguration config                Environment   env          Configuration   config          var myconfig   Configuration  MyConfig               public IConfiguration Configuration   get        public IHostingEnvironment Environment   get

User · Answer

Just create An AnyName cs file and paste following code   using System  using System IO  using Microsoft Extensions Configuration   namespace Custom       static class ConfigurationManager               public static IConfiguration AppSetting   get            static ConfigurationManager                         AppSetting   new ConfigurationBuilder                        SetBasePath Directory GetCurrentDirectory                         AddJsonFile  YouAppSettingFile json                        Build                        Must replace YouAppSettingFile json file name with your file name  Your  json file should look like below          GrandParent Key               Parent Key                   Child Key     value1                        Parent Key               Child Key     value2              Child Key     value3      Now you can use it  Don t forget to Add Reference in your class where you want to use   using Custom    Code to retrieve value   string value1   ConfigurationManager AppSetting  GrandParent Key Parent Key Child Key    string value2   ConfigurationManager AppSetting  Parent Key Child Key    string value3   ConfigurationManager AppSetting  Child Key

User · Answer

public static void GetSection                 Configuration   new ConfigurationBuilder                SetBasePath env ContentRootPath               AddJsonFile  appsettings json                Build             string BConfig   Configuration GetSection  ConnectionStrings    BConnection

User · Answer

NET core 3 X no need to create new model and to set in Startup cs  Controller Add new package - using Microsoft Extensions Configuration  public class HomeController   Controller       private readonly IConfiguration  mySettings       public HomeController  IConfiguration mySettings                  mySettings  mySettings                ex  you can get value on below function      public IEnumerable lt string gt  Get                 var result    config GetValue lt string gt   quot AppSettings Version quot        quot One quot          return new string     result ToString

User · Answer

Its simple  In appsettings json    quot MyValues quot          quot Value1 quot    quot Xyz quot       In  cs file  static IConfiguration conf    new ConfigurationBuilder   SetBasePath Directory GetCurrentDirectory    AddJsonFile  quot appsettings json quot   Build             public static string myValue1  conf  quot MyValues Value1 quot   ToString

User · Answer

Add the required key here like this  In this case its SecureCookies     In startup cs  add the constructor  public Startup IConfiguration configuration          Configuration   configuration       public IConfiguration Configuration   get      Access the settings using Configuration  quot SecureCookies quot

User · Answer

I guess the simplest way is by DI  An example of reaching into Controller      StartUp cs public void ConfigureServices IServiceCollection services                   for get appsettings from anywhere     services AddSingleton Configuration      public class ContactUsController   Controller       readonly IConfiguration  configuration       public ContactUsController          IConfiguration configuration                 configuration   configuration              sample          var apiKey    configuration GetValue lt string gt   SendGrid CAAO

User · Answer

From Asp net core 2 2 to above you can code as below   Step 1  Create an AppSettings class file   This file contains some methods to help get value by key from the appsettings json file  Look like as code below   using System  using System Collections Generic  using System Linq  using System Threading Tasks   namespace ReadConfig Bsl     public class AppSettings           private static AppSettings  instance        private static readonly object ObjLocked   new object          private IConfiguration  configuration         protected AppSettings                          public void SetConfiguration IConfiguration configuration                     configuration   configuration                 public static AppSettings Instance                   get                           if  null     instance                                    lock  ObjLocked                                            if  null     instance                             instance   new AppSettings                                                      return  instance                             public string GetConnection string key  string defaultValue                         try                           return  configuration GetConnectionString key                         catch                           return defaultValue                             public T Get lt T gt  string key   null                    if  string IsNullOrWhiteSpace key                 return  configuration Get lt T gt               else               return  configuration GetSection key  Get lt T gt                    public T Get lt T gt  string key  T defaultValue                    if   configuration GetSection key     null                return defaultValue             if  string IsNullOrWhiteSpace key                 return  configuration Get lt T gt               else               return  configuration GetSection key  Get lt T gt                    public static T GetObject lt T gt  string key   null                    if  string IsNullOrWhiteSpace key                 return Instance  configuration Get lt T gt               else                           var section   Instance  configuration GetSection key                 return section Get lt T gt                                public static T GetObject lt T gt  string key  T defaultValue                    if  Instance  configuration GetSection key     null                return defaultValue             if  string IsNullOrWhiteSpace key                 return Instance  configuration Get lt T gt               else               return Instance  configuration GetSection key  Get lt T gt                     Step 2  Initial configuration for AppSettings object  We need to declare and load appsettings json file when the application starts  and load configuration information for AppSettings object  We will do this work in the constructor of the Startup cs file   Please notice line AppSettings Instance SetConfiguration Configuration      public Startup IHostingEnvironment evm        var builder   new ConfigurationBuilder          SetBasePath evm ContentRootPath         AddJsonFile  appsettings json   true  true         AddJsonFile   appsettings  evm EnvironmentName  json   true         AddEnvironmentVariables        Configuration   builder Build       load all file config to Configuration property      AppSettings Instance SetConfiguration Configuration              Okay  now I have an appsettings json file with some keys as below        Logging          LogLevel            Default    Information          Microsoft    Warning          Microsoft Hosting Lifetime    Information                AllowedHosts           ConnectionStrings          ConnectionString    Data Source localhost Initial Catalog ReadConfig Persist Security Info True User ID sa Password 12345           MailConfig          Servers            MailGun              Pass    65-1B-C9-B9-27-00            Port    587            Host    smtp gmail com                      Sender            Email    example gmail com          Pass    123456                Step 3  Read config value from an action  I make demo an action in Home controller as below    public class HomeController   Controller       public IActionResult Index                 var connectionString   AppSettings Instance GetConnection  ConnectionString            var emailSender   AppSettings Instance Get lt string gt   MailConfig Sender Email            var emailHost   AppSettings Instance Get lt string gt   MailConfig Servers MailGun Host             string returnText     1  Connection String  n           returnText          connectionString          returnText      n 2  Email info           returnText      n Sender       emailSender          returnText      n Host       emailHost           return Content returnText             And below is the result   Click to see result  For more information  you can refer article get value from appsettings json in asp net core for more detail code

[c#] Getting value from appsettings.json in .net core

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