How to modify my App.exe.config keys at runtime?

c# .net app-config
Louis Rhys picture Louis Rhys · Mar 29, 2011 · Viewed 63.9k times · Source

In my app.config I have this section

<appSettings>
    <add key ="UserId" value ="myUserId"/>
     // several other <add key>s
</appSettings>

Usually I access the values using userId = ConfigurationManager.AppSettings["UserId"]

If I modify it using ConfigurationManager.AppSettings["UserId"]=something, the value is not saved to the file, and next time I load the application, it uses the old value.

How can I change the value of some app.config keys during runtime?

Answer

Rafal Spacjer picture Rafal Spacjer · Mar 29, 2011 
System.Configuration.Configuration config = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);

config.AppSettings.Settings["UserId"].Value = "myUserId";     
config.Save(ConfigurationSaveMode.Modified);

You can read about ConfigurationManager here

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