WPF application , modify the App.Config file from compiled application

Question

I have probably misunderstood the documentation because i'm a hack :p. But is the App.Config a read-only situation in a WPF application?

System.ConfigurationManager.AppSettings seems to have a "Set" and "Get" method . But for the life of me I can not get the "Set" method to modify this file in a compiled application. I have a DatabaseName field in my App.Config etc.. and i'm pretty sure i'm calling it correctly.

App.Config File

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<appSettings>
<add key="DatabaseName" value=""/>
<add key="DatabaseUsername" value=""/>
<add key="DatabasePassword" value=""/>
</appSettings>
</configuration>

Calling Code

ConfigurationManager.AppSettings.Set("DatabaseName", someDatabaseNameString);

I'm guessing this is by-design ( a sort of safe-place for application-wide settings) . If this is the case I guess i can just store "application-wide" parameters that need to be changed by the application in a different config file.

But would be good to know if this is the case. Would much rather have one config file then two.

(P.S) yes im running the compiled application and checking to see if the <ApplicationName>.dll.config is been changed

Thanks

Answer 1

@Kapanther , Welcome to Microsoft Q&A, based on my test, I reproduced your problem.
I recommend that you use the following code to change your app.config value.

private void btntest_Click(object sender, RoutedEventArgs e)  
        {  
            AddUpdateAppSettings("DatabaseName", "connstr");  
        AddUpdateAppSettings("DatabaseUsername", "testuser");  
        AddUpdateAppSettings("DatabasePassword", "password");  
        }  
  
        public void AddUpdateAppSettings(string key, string value)  
        {  
            try  
            {  
                System.Configuration.ExeConfigurationFileMap fileMap = new ExeConfigurationFileMap();  
                fileMap.ExeConfigFilename = AppDomain.CurrentDomain.BaseDirectory + "..\\..\\App.config";  
                Configuration configFile = ConfigurationManager.OpenMappedExeConfiguration(fileMap, ConfigurationUserLevel.None);  
                var settings = configFile.AppSettings.Settings;  
                if (settings[key] == null)  
                {  
                    settings.Add(key, value);  
                }  
                else  
                {  
                    settings[key].Value = value;  
                }  
                configFile.Save(ConfigurationSaveMode.Modified);  
                ConfigurationManager.RefreshSection(configFile.AppSettings.SectionInformation.Name);  
            }  
            catch (ConfigurationErrorsException)  
            {  
                Console.WriteLine("Error writing app settings");  
            }  
        }  

Result:

Best Regards,
Jack

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