How to read AppSettings values from a json file in ASP NET Core

Question

I have set up my AppSettings data in file appsettings Config  json like this        AppSettings              token    1234            I have searched online on how to read AppSettings values from  json file  but I could not get anything useful   I tried   var configuration   new Configuration    var appSettings   configuration Get  AppSettings       null var token   configuration Get  token       null   I know with ASP NET 4 0 you can do this   System Configuration ConfigurationManager AppSettings  token      But how do I do this in ASP NET Core

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NET Core 2 1 0   Create the  json file on the root directory On your code     var builder   new ConfigurationBuilder                    SetBasePath Directory GetCurrentDirectory                     AddJsonFile  appsettings json   optional  true  reloadOnChange  true       var config   builder Build      3  Install the following dependencies   Microsoft Extensions Configuration Microsoft Extensions Configuration json   4  Then  IMPORTANT   Right-click on the appsettings json file -  click on Properties -  select Copy if newer     Finally  you can do   config  key1     Considering that my config file will look like this           ConnectionStrings    myconnection string here        key1    value here

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They just keep changing things     having just updated Visual nbsp Studio and had the whole project bomb  on the road to recovery and the new way looks like this   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 IsDevelopment                     For more details on using the user secret store see http   go microsoft com fwlink  LinkID 532709         builder AddUserSecrets               builder AddEnvironmentVariables        Configuration   builder Build        I kept missing this line    SetBasePath env ContentRootPath

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This has had a few twists and turns  I ve modified this answer to be up to date with ASP NET Core 2 0  as of 26 02 2018    This is mostly taken from the official documentation   To work with settings in your ASP NET application  it is recommended that you only instantiate a Configuration in your application   s Startup class  Then  use the Options pattern to access individual settings  Let s say we have an appsettings json file that looks like this        MyConfig         ApplicationName    MyApp       Version    1 0 0            And we have a POCO object representing the configuration   public class MyConfig       public string ApplicationName   get  set        public int Version   get  set        Now we build the configuration in Startup cs   public class Startup        public IConfigurationRoot Configuration   get  set         public Startup IHostingEnvironment env                var builder   new ConfigurationBuilder                SetBasePath env ContentRootPath               AddJsonFile  appsettings json   optional  true  reloadOnChange  true            Configuration   builder Build              Note that appsettings json will be registered by default in  NET Core 2 0  We can also register an appsettings  Environment  json config file per environment if needed   If we want to inject our configuration to our controllers  we ll need to register it with the runtime  We do so via Startup ConfigureServices   public void ConfigureServices IServiceCollection services        services AddMvc            Add functionality to inject IOptions lt T gt      services AddOptions            Add our Config object so it can be injected     services Configure lt MyConfig gt  Configuration GetSection  MyConfig         And we inject it like this   public class HomeController   Controller       private readonly IOptions lt MyConfig gt  config       public HomeController IOptions lt MyConfig gt  config                this config   config                GET    lt controller gt       public IActionResult Index     gt  View config Value       The full Startup class   public class Startup        public IConfigurationRoot Configuration   get  set         public Startup IHostingEnvironment env                var builder   new ConfigurationBuilder                SetBasePath env ContentRootPath               AddJsonFile  appsettings json   optional  true  reloadOnChange  true            Configuration   builder Build               public void ConfigureServices IServiceCollection services                services AddMvc                Add functionality to inject IOptions lt T gt          services AddOptions                Add our Config object so it can be injected         services Configure lt MyConfig gt  Configuration GetSection  MyConfig

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The  NET Core 2 2 way   No doubt Microsoft will change it again to something completely different in the next  NET version    1  appSettings json  It may look something like this  Here we will be loading Setting1 and Setting2       Logging          LogLevel            Default    Warning                AllowedHosts           Setting1    abc      Setting2   123     2  AppSettings cs  The POCO class to hold Setting1 and Setting2  We will be loading the appsettings json into this class object  The structure of the POCO class should match the JSON file  properties may be nested within other properties classes if desired   public class AppSettings       public string Setting1   get  set        public int Setting2   get  set        3 Startup cs  Load appSettings json into you AppSettings object and start using it   public class Startup       public Startup IConfiguration configuration                AppSettings settings   new AppSettings             Configuration   configuration          configuration Bind settings               Now start using it         string setting1   settings Setting1          int setting2   settings Setting2

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I doubt this is good practice but it s working locally  I ll update this if it fails when I publish deploy  to an IIS web service    Step 1 - Add this assembly to the top of your class  in my case  controller class    using Microsoft Extensions Configuration    Step 2 - Add this or something like it   var config   new ConfigurationBuilder                    SetBasePath Directory GetCurrentDirectory                     AddJsonFile  appsettings json   Build      Step 3 - Call your key s value by doing this  returns string    config  NameOfYourKey

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If you just want to get the value of the token then use  Configuration  AppSettings token

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Just to complement the Yuval Itzchakov answer   You can load configuration without builder function  you can just inject it   public IConfiguration Configuration   get  set     public Startup IConfiguration configuration       Configuration   configuration

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The following works for console applications    Install the following NuGet packages   csproj     lt ItemGroup gt       lt PackageReference Include  Microsoft Extensions Configuration  Version  2 2 0-preview2-35157    gt       lt PackageReference Include  Microsoft Extensions Configuration FileExtensions  Version  2 2 0-preview2-35157    gt       lt PackageReference Include  Microsoft Extensions Configuration Json  Version  2 2 0-preview2-35157    gt   lt  ItemGroup gt   Create appsettings json at root level  Right click on it and  Copy to Output Directory  as  Copy if newer   Sample configuration file        AppConfig          FilePath    C   temp  logs  output txt         Program cs  configurationSection Key and configurationSection Value will have config properties   static void Main string   args        try                IConfigurationBuilder builder   new ConfigurationBuilder                SetBasePath Directory GetCurrentDirectory                 AddJsonFile  appsettings json   optional  true  reloadOnChange  true            IConfigurationRoot configuration   builder Build               configurationSection Key   gt  FilePath            configurationSection Value   gt  C   temp  logs  output txt         IConfigurationSection configurationSection   configuration GetSection  AppConfig   GetSection  FilePath               catch  Exception e                Console WriteLine e

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With the latest iteration of netcoreapp 3 1 out  you can do this pretty simply without any third-party dependencies   I created a gist for this  but you can use this class to read a JSON file and return dynamic properties   using System Text Json  using System IO   class ConfigurationLoader        private dynamic configJsonData      public ConfigurationLoader Load string configFilePath    appsettings json                 var appSettings   File ReadAllText configFilePath           this configJsonData   JsonSerializer Deserialize appSettings  typeof object            return this             public dynamic GetProperty string key                var properties   key Split               dynamic property   this configJsonData          foreach  var prop in properties                        property   property GetProperty prop                      return property            I specifically made this so I could use an appconfig json in my dotnet console application  I just put this in my Program Main function   var config   new ConfigurationLoader    config Load    Console WriteLine config GetProperty  Environment Name       And this will return a dynamic object for the property   A JsonElement if it s not a primitive   My appsettings json file looks like this        Environment          Token    abc-123        Name    Production

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With  NET Core 2 2  and in the simplest way possible     public IActionResult Index  FromServices  IConfiguration config        var myValue   config GetValue lt string gt   MyKey        appsettings json is automatically loaded and available through either constructor or action injection  and there s a GetSection method on IConfiguration as well  There isn t any need to alter Startup cs or Program cs if all you need is appsettings json

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Get it inside controller as an object via call Get lt YourType gt      public IActionResult Index  FromServices  IConfiguration config        BillModel model   config GetSection  Yst Requisites   Get lt BillModel gt         return View model

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You can try below code  This is working for me   public class Settings       private static IHttpContextAccessor  HttpContextAccessor       public Settings IHttpContextAccessor httpContextAccessor                 HttpContextAccessor   httpContextAccessor             public static void Configure IHttpContextAccessor httpContextAccessor                 HttpContextAccessor   httpContextAccessor             public static IConfigurationBuilder Getbuilder                 var builder   new ConfigurationBuilder              SetBasePath Directory GetCurrentDirectory               AddJsonFile  appsettings json            return builder             public static string GetAppSetting string key                  return Convert ToString ConfigurationManager AppSettings key            var builder   Getbuilder            var GetAppStringData   builder Build   GetValue lt string gt   AppSettings     key           return GetAppStringData             public static string GetConnectionString string key  DefaultName                 var builder   Getbuilder            var ConnectionString   builder Build   GetValue lt string gt   ConnectionStrings   key           return ConnectionString            Here I have created one class to get connection string and app settings   I Startup cs file you need to register class as below   public class Startup        public void Configure IApplicationBuilder app  IHostingEnvironment env                var httpContextAccessor   app ApplicationServices GetRequiredService lt IHttpContextAccessor gt             Settings Configure httpContextAccessor

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Here s the full use-case for ASP NET Core   articles json       shownArticlesCount   3     articles                  title    My Title 1          thumbnailLink    example com img1 png          authorProfileLink    example com   alper          authorName    Alper Ebicoglu          publishDate    2018-04-17          text                 link                             title    My Title 2          thumbnailLink    example com img2 png          authorProfileLink    example com   alper          authorName    Alper Ebicoglu          publishDate    2018-04-17          text                 link                          ArticleContainer cs  public class ArticleContainer       public int ShownArticlesCount   get  set         public List lt Article gt  Articles   get  set       public class Article       public string Title   get  set         public string ThumbnailLink   get  set         public string AuthorName   get  set         public string AuthorProfileLink   get  set         public DateTime PublishDate   get  set         public string Text   get  set         public string Link   get  set           Startup cs  public class Startup       public IConfigurationRoot ArticleConfiguration   get  set         public Startup IHostingEnvironment env                ArticleConfiguration   new ConfigurationBuilder                SetBasePath env ContentRootPath               AddJsonFile  articles json                Build               public IServiceProvider ConfigureServices IServiceCollection services                services AddOptions             services Configure lt ArticleContainer gt  ArticleConfiguration               Index cshtml cs  public class IndexModel   PageModel       public ArticleContainer ArticleContainer   get set         private readonly IOptions lt ArticleContainer gt   articleContainer       public IndexModel IOptions lt ArticleContainer gt  articleContainer                 articleContainer   articleContainer             public void OnGet                 ArticleContainer    articleContainer Value              Index cshtml cs   lt h1 gt  Model ArticleContainer ShownArticlesCount lt  h1 gt

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In addition to existing answers I d like to mention that sometimes it might be useful to have extension methods for IConfiguration for simplicity s sake   I keep JWT config in appsettings json so my extension methods class looks as follows   public static class ConfigurationExtensions       public static string GetIssuerSigningKey this IConfiguration configuration                string result   configuration GetValue lt string gt   Authentication JwtBearer SecurityKey            return result             public static string GetValidIssuer this IConfiguration configuration                string result   configuration GetValue lt string gt   Authentication JwtBearer Issuer            return result             public static string GetValidAudience this IConfiguration configuration                string result   configuration GetValue lt string gt   Authentication JwtBearer Audience            return result             public static string GetDefaultPolicy this IConfiguration configuration                string result   configuration GetValue lt string gt   Policies Default            return result             public static SymmetricSecurityKey GetSymmetricSecurityKey this IConfiguration configuration                var issuerSigningKey   configuration GetIssuerSigningKey            var data   Encoding UTF8 GetBytes issuerSigningKey           var result   new SymmetricSecurityKey data           return result             public static string   GetCorsOrigins this IConfiguration configuration                string   result               configuration GetValue lt string gt   App CorsOrigins                Split      StringSplitOptions RemoveEmptyEntries               ToArray             return result            It saves you a lot of lines and you just write clean and minimal code       x TokenValidationParameters   new TokenValidationParameters         ValidateIssuerSigningKey   true      ValidateLifetime   true      IssuerSigningKey    configuration GetSymmetricSecurityKey        ValidAudience    configuration GetValidAudience        ValidIssuer    configuration GetValidIssuer          It s also possible to register IConfiguration instance as singleton and inject it wherever you need - I use Autofac container here s how you do it   var appConfiguration   AppConfigurations Get WebContentDirectoryFinder CalculateContentRootFolder     builder Register c   gt  appConfiguration  As lt IConfigurationRoot gt    SingleInstance      You can do the same with MS Dependency Injection   services AddSingleton lt IConfigurationRoot gt  appConfiguration

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First you should inject IConfiguration and then for reading from appsettings  you can use one of this methods    Get a section data  var redisConfig   configuration GetSection  RedisConfig     Get a value within a section  var redisServer   configuration GetValue lt string gt   RedisConfig ServerName     Get nested value within section  var redisExpireMInutes   configuration GetValue lt int gt   RedisConfig ServerName ExpireMInutes

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Was this  cheating    I just made my Configuration in the Startup class static  and then I can access it from anywhere else   public class Startup          This method gets called by the runtime  Use this method to add services to the container         For more information on how to configure your application  visit https   go microsoft com fwlink  LinkID 398940     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               AddEnvironmentVariables             Configuration   builder Build               public static IConfiguration Configuration   get  set

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For  NET Core 2 0  things have changed a little bit  The startup constructor takes a Configuration object as a parameter  So using the ConfigurationBuilder is not required  Here is mine   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 Configure lt StorageOptions gt  Configuration GetSection  AzureStorageConfig         My POCO is the StorageOptions object mentioned at the top   namespace FictionalWebApp Models       public class StorageOptions               public String StorageConnectionString   get  set            public String AccountName   get  set            public String AccountKey   get  set            public String DefaultEndpointsProtocol   get  set            public String EndpointSuffix   get  set             public StorageOptions                 And the configuration is actually a subsection of my appsettings json file  named AzureStorageConfig        ConnectionStrings          DefaultConnection    Server  localdb   mssqllocaldb         StorageConnectionString    DefaultEndpointsProtocol https AccountName fictionalwebapp AccountKey Cng4Afwlk242-23 - d2ksa69 2xM0jLUUxoAw   EndpointSuffix core windows net          Logging          IncludeScopes   false       LogLevel            Default    Warning                 AzureStorageConfig          AccountName    fictionalwebapp        AccountKey    Cng4Afwlk242-23 - d2ksa69 2xM0jLUUxoAw          DefaultEndpointsProtocol    https        EndpointSuffix    core windows net        StorageConnectionString    DefaultEndpointsProtocol https AccountName fictionalwebapp AccountKey Cng4Afwlk242-23 - d2ksa69 2xM0jLUUxoAw   EndpointSuffix core windows net          The only thing I ll add is that  since the constructor has changed  I haven t tested whether something extra needs to be done for it to load appsettings  lt environmentname gt  json as opposed to appsettings json

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NET Core 3 0  Maybe it is not the best way to get a value from appsettings json  but it is simple and it works in my application    File appsettings json         ConnectionStrings              DefaultConnection                     AppSettings              APP Name    MT Service            APP Version     1 0 0            Controller   On top   using Microsoft Extensions Configuration    In your code   var AppName   new ConfigurationBuilder   AddJsonFile  appsettings json   Build   GetSection  AppSettings    APP Name

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First off  The assembly name and namespace of Microsoft Framework ConfigurationModel has changed to Microsoft Framework Configuration  So you should use  e g    Microsoft Framework Configuration Json    1 0 0-beta7    as a dependency in project json  Use beta5 or 6 if you don t have 7 installed  Then you can do something like this in Startup cs   public IConfiguration Configuration   get  set     public Startup IHostingEnvironment env  IApplicationEnvironment appEnv         var configurationBuilder   new ConfigurationBuilder appEnv ApplicationBasePath           AddJsonFile  config json            AddEnvironmentVariables         Configuration   configurationBuilder Build        If you then want to retrieve a variable from the config json you can get it right away using   public void Configure IApplicationBuilder app           Add  Value to get the token string     var token   Configuration GetSection  AppSettings token        app Run async  context    gt                await context Response WriteAsync  This is a token with key      token Key          token Value               or you can create a class called AppSettings like this   public class AppSettings       public string token   get  set        and configure the services like this   public void ConfigureServices IServiceCollection services               services AddMvc         services Configure lt MvcOptions gt  options   gt                  mvc options              services Configure lt AppSettings gt  Configuration GetSection  AppSettings         and then access it through e g  a controller like this   public class HomeController   Controller       private string  token       public HomeController IOptions lt AppSettings gt  settings                 token   settings Options token

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For ASP NET Core 3 1 you can follow this documentation   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

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Super late to the party but if someone finds this out  You can call IConfiguration from Microsoft Extensions Configuration  public static IConfiguration Configuration   get    public static string MyAwesomeString   Configuration GetSection  quot appSettings quot    quot MyAwesomeString quot   ToString

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For  NET Core 2 0  you can simply   Declare your key value pairs in appsettings json        MyKey    MyValue      Inject the configuration service in startup cs  and get the value using the service  using Microsoft Extensions Configuration   public class Startup       public void Configure IConfiguration configuration                                other injected services                                           app Run async  context    gt                        string myValue   configuration  MyKey                await context Response WriteAsync myValue

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