Reading settings from app config or web config in NET

Question

I m working on a C  class library that needs to be able to read settings from the web config or app config file  depending on whether the DLL is referenced from an ASP NET web application or a Windows Forms application    I ve found that  ConfigurationSettings AppSettings Get  MySetting     works  but that code has been marked as deprecated by Microsoft   I ve read that I should be using   ConfigurationManager AppSettings  MySetting     However  the System Configuration ConfigurationManager class doesn t seem to be available from a C  Class Library project   What is the best way to do this

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I strongly recommend you to create a wrapper for this call  Something like a ConfigurationReaderService and use dependency injection to get this class  This way you will be able to isolate this configuration files for test purposes   So use the ConfigurationManager AppSettings  something    suggested and return this value  With this method you can create some kind of default return if there isn t any key available in the  config file

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You must add a reference to the System Configuration assembly to the project

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Try this   string keyvalue   System Configuration ConfigurationManager AppSettings  keyname      In the web config file this should be the next structure    lt configuration gt   lt appSettings gt   lt add key  keyname  value  keyvalue    gt   lt  appSettings gt   lt  configuration gt

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Right click on your class library  and choose the  Add References  option from the Menu   And from the  NET tab  select System Configuration  This would include the System Configuration DLL file into your project

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Another possible solution   var MyReader   new System Configuration AppSettingsReader    string keyvalue   MyReader GetValue  keyalue  typeof string   ToString

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Please check the  NET version you are working on  It should be higher than 4  And you have to add the System Configuration system library to your application

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Update for  NET Framework 4 5 and 4 6  the following will no longer work   string keyvalue   System Configuration ConfigurationManager AppSettings  keyname      Now access the Setting class via Properties   string keyvalue   Properties Settings Default keyname      See Managing Application Settings for more information

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I always create an IConfig interface with typesafe properties declared for all configuration values  A Config implementation class then wraps the calls to System Configuration  All your System Configuration calls are now in one place  and it is so much easier and cleaner to maintain and track which fields are being used and declare their default values  I write a set of private helper methods to read and parse common data types   Using an IoC framework you can access the IConfig fields anywhere your in application by simply passing the interface to a class constructor  You re also then able to create mock implementations of the IConfig interface in your unit tests so you can now test various configuration values and value combinations without needing to touch your App config or Web config file

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Step 1  Right-click on references tab to add reference   Step 2  Click on Assemblies tab  Step 3  Search for  System Configuration   Step 4  Click OK   Then it will work    string value   System Configuration ConfigurationManager AppSettings  keyname

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I was able to get the below approach working for  NET Core projects   Steps    Create an appsettings json  format given below  in your project  Next create a configuration class  The format is provided below  I have created a Login   method to show the usage of the Configuration Class   Create appsettings json in your project with content        Environments          QA            Url    somevalue     Username    someuser          Password    somepwd          BrowserConfig          Browser    Chrome        Headless    true          EnvironmentSelected          Environment    QA         public static class Configuration       private static IConfiguration  configuration       static Configuration                 var builder   new ConfigurationBuilder                AddJsonFile   appsettings json              configuration   builder Build               public static Browser GetBrowser                  if   configuration GetSection  BrowserConfig Browser   Value     Firefox                         return Browser Firefox                    if   configuration GetSection  BrowserConfig Browser   Value     Edge                         return Browser Edge                    if   configuration GetSection  BrowserConfig Browser   Value     IE                         return Browser InternetExplorer                    return Browser Chrome             public static bool IsHeadless                 return  configuration GetSection  BrowserConfig Headless   Value     true              public static string GetEnvironment                 return  configuration GetSection  EnvironmentSelected    Environment              public static IConfigurationSection EnvironmentInfo                 var env   GetEnvironment            return  configuration GetSection    Environments  env                public void Login         var environment   Configuration EnvironmentInfo        Email SendKeys environment  username         Password SendKeys environment  password         WaitForElementToBeClickableAndClick  driver  SignIn

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You can use the below line  In my case it was working      System Configuration ConfigurationSettings AppSettings  yourKeyName    You must take care that the above line of code is also the old version and it s deprecated in new libraries

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As I found the best approach to access application settings variables in a systematic way by making a wrapper class over System Configuration as below  public class BaseConfiguration       protected static object GetAppSetting Type expectedType  string key                string value   ConfigurationManager AppSettings Get key           try                       if  expectedType    typeof int                   return int Parse value               if  expectedType    typeof string                   return value               throw new Exception  Type not supported                       catch  Exception ex                        throw new Exception string Format  Config key  0  was expected to be of type  1  but was not                    key  expectedType   ex                       Now we can access needed settings variables by hard coded names using another class as below   public class ConfigurationSettings BaseConfiguration        region App setting      public static string ApplicationName               get   return  string GetAppSetting typeof string    ApplicationName                 public static string MailBccAddress               get   return  string GetAppSetting typeof string    MailBccAddress                 public static string DefaultConnection               get   return  string GetAppSetting typeof string    DefaultConnection                  endregion App setting       region global setting        endregion global setting

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Read From Config   You ll need to add a reference to the configuration    Open  Properties  on your project Go to  Settings  Tab Add  Name  and  Value  Get Value with using following code   string value   Properties Settings Default keyname     Save to the configuration      Properties Settings Default keyName   value     Properties Settings Default Save

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I m using this  and it works well for me   textBox1 Text   ConfigurationManager AppSettings  Name

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I had the same problem  Just read them this way      System Configuration ConfigurationSettings AppSettings  MySetting

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I have been trying to find a fix for this same issue for a couple of days now  I was able to resolve this by adding a key within the appsettings tag in the web config file  This should override the  dll file when using the helper    lt configuration gt       lt appSettings gt           lt add key  loginUrl  value    RedirectValue cshtml    gt           lt add key  autoFormsAuthentication  value  false   gt       lt  appSettings gt   lt  configuration gt

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The ConfigurationManager is not what you need to access your own settings   To do this you should use   YourAppName  Properties Settings  settingName

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web config is used with web applications  web config by default has several configurations required for the web application  You can have a web config for each folder under your web application   app config is used for Windows applications  When you build the application in Visual Studio  it will be automatically renamed to  lt appname gt  exe config and this file has to be delivered along with your application   You can use the same method to call the app settings values from both configuration files      System Configuration ConfigurationSettings AppSettings  Key

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You might be adding the App config file to a DLL file  App Config works only for executable projects  since all the DLL files take the configuration from the configuration file for the EXE file being executed   Let s say you have two projects in your solution    SomeDll SomeExe   Your problem might be related to the fact that you re including the app config file to SomeDLL and not SomeExe  SomeDll is able to read the configuration from the SomeExe project

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If your needing wanting to use the ConfigurationManager class     You may need to load System Configuration ConfigurationManager by Microsoft via NuGet Package Manager     Tools- NuGet Package Manager- Manage NuGet Packages for Solution      Microsoft Docs  One thing worth noting from the docs        If your application needs read-only access to its own configuration    we recommend that you use the GetSection String  method  This method   provides access to the cached configuration values for the current   application  which has better performance than the Configuration   class

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You ll need to add a reference to System Configuration in your project s references folder     You should definitely be using the ConfigurationManager over the obsolete ConfigurationSettings

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Here s an example  App config   lt applicationSettings gt       lt MyApp My MySettings gt           lt setting name  Printer  serializeAs  String  gt               lt value gt 1234  lt  value gt           lt  setting gt       lt  MyApp My MySettings gt   lt  applicationSettings gt   Dim strPrinterName as string   My settings Printer

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Also  you can use Formo   Configuration    lt appSettings gt       lt add key  RetryAttempts  value  5    gt       lt add key  ApplicationBuildDate  value  11 4 1999 6 23 AM    gt   lt  appSettings gt    Code   dynamic config   new Configuration    var retryAttempts1   config RetryAttempts                     Returns 5 as a string var retryAttempts2   config RetryAttempts 10                  Returns 5 if found in config  else 10 var retryAttempts3   config RetryAttempts userInput  10       Returns 5 if it exists in config  else userInput if not null  else 10 var appBuildDate   config ApplicationBuildDate lt DateTime gt

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For a sample app config file like below    lt  xml version  1 0  encoding  utf-8    gt   lt configuration gt     lt appSettings gt       lt add key  countoffiles  value  7    gt       lt add key  logfilelocation  value  abc txt    gt     lt  appSettings gt   lt  configuration gt    You read the above application settings using the code shown below   using System Configuration    You may also need to also add a reference to System Configuration in your project if there isn t one already  You can then access the values like so   string configvalue1   ConfigurationManager AppSettings  countoffiles    string configvalue2   ConfigurationManager AppSettings  logfilelocation

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Just for completeness  there s another option available for web projects only      System Web Configuration WebConfigurationManager AppSettings  MySetting    The benefit of this is that it doesn t require an extra reference to be added  so it may be preferable for some people

[c#] Reading settings from app.config or web.config in .NET

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