How to change in runtime application settings

Question

I'm trying to change in runtime one key of my applications settings file, but it does not work.

I do on that way:

ConfigurationSettings.AppSettings["XPTO"] = "HELLO";

It seems that it only changes in memory, not on the file.

Does anyone knows how to do this?

Thanks.

Answer 1

Take a look at my overview of .NET settings files...In short, I think you want a user-scoped setting. It will behave more like you expect.

Edit: If you are using the settings designer in Visual Studio, then simply change the "Scope" to "User". If not, you should be able to do the equivalent programmatically.

Answer 2

The AppSettings file is not designed to be writable. It is designed to store configurations that will not change at run time but might change over time ie: DB Connection Strings, web service URL's, etc.

So, while it may be possible to update the file in reality you should re-asses if this value should be stored there.

Answer 3

Assuming your app has write permissions on the file...

    Configuration config = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);  // the config that applies to all users
    AppSettingsSection appSettings = config.AppSettings;

    if (appSettings.IsReadOnly() == false)
    {
        appSettings("Key").Value = "new value";

        config.Save();
    }

I'm ignoring all the possible exceptions that can be thrown...