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Update AppSettings and custom configuration sections in App.config at runtime

Published: August 31, 2013 by Yi Zeng

Categories:
tutorials 26

This post shows how to update (add, edit or remove) AppSettings and custom config sections in App.config at runtime.

App.config file
Update AppSettings
Update custom configuration sections
Print out all keys
References

App.config file

Sample App.config file:

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
    <configSections>
        <sectionGroup name="geoSettings">
            <section name="summary" type="System.Configuration.NameValueSectionHandler" />
        </sectionGroup>
    </configSections>

    <appSettings>
        <add key="Language" value="Ruby" />
        <add key="Version" value="1.9.3" />
    </appSettings>

    <geoSettings>
        <summary>
            <add key="Country" value="New Zealand" />
            <add key="City" value="Christchurch" />
        </summary>
    </geoSettings>
</configuration>

Update AppSettings

Add a new key

var config = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);
config.AppSettings.Settings.Add("OS", "Linux");
config.Save(ConfigurationSaveMode.Modified);

ConfigurationManager.RefreshSection("appSettings");

Edit an existing key's value

var config = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);
config.AppSettings.Settings["Version"].Value = "2.0.0";
config.Save(ConfigurationSaveMode.Modified);

ConfigurationManager.RefreshSection("appSettings");

Delete an existing key

var config = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);
config.AppSettings.Settings.Remove("Version");
config.Save(ConfigurationSaveMode.Modified);

ConfigurationManager.RefreshSection("appSettings");

Update custom configuration sections

Add a new key

var xmlDoc = new XmlDocument();
xmlDoc.Load(AppDomain.CurrentDomain.SetupInformation.ConfigurationFile);

// create new node <add key="Region" value="Canterbury" />
var nodeRegion = xmlDoc.CreateElement("add");
nodeRegion.SetAttribute("key", "Region");
nodeRegion.SetAttribute("value", "Canterbury");

xmlDoc.SelectSingleNode("//geoSettings/summary").AppendChild(nodeRegion);
xmlDoc.Save(AppDomain.CurrentDomain.SetupInformation.ConfigurationFile);

ConfigurationManager.RefreshSection("geoSettings/summary");

Edit an existing key's value

var xmlDoc = new XmlDocument();
xmlDoc.Load(AppDomain.CurrentDomain.SetupInformation.ConfigurationFile);

xmlDoc.SelectSingleNode("//geoSettings/summary/add[@key='Country']").Attributes["value"].Value = "Old Zeeland";
xmlDoc.Save(AppDomain.CurrentDomain.SetupInformation.ConfigurationFile);

ConfigurationManager.RefreshSection("geoSettings/summary");

Delete an existing key

var xmlDoc = new XmlDocument();
xmlDoc.Load(AppDomain.CurrentDomain.SetupInformation.ConfigurationFile);

XmlNode nodeCity = xmlDoc.SelectSingleNode("//geoSettings/summary/add[@key='City']");
nodeCity.ParentNode.RemoveChild(nodeCity);

xmlDoc.Save(AppDomain.CurrentDomain.SetupInformation.ConfigurationFile);
ConfigurationManager.RefreshSection("geoSettings/summary");

Print out all keys

var appSettings = ConfigurationManager.AppSettings;
var customSettings = ConfigurationManager.GetSection("geoSettings/summary") as NameValueCollection;

foreach (string key in appSettings.AllKeys) {
    Console.WriteLine("{0}: {1}", key, appSettings[key]);
}
foreach (string key in customSettings.AllKeys) {
    Console.WriteLine("{0}: {1}", key, customSettings[key]);
}

References