Change App.config during installation

Question

I have XML-file with settings like this

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
    <configSections>
        <sectionGroup name="applicationSettings" type="System.Configuration.ApplicationSettingsGroup, System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" >
            <section name="UpdateReportService.Properties.Settings" type="System.Configuration.ClientSettingsSection, System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" requirePermission="false" />
        </sectionGroup>
    </configSections>
    <applicationSettings>
        <UpdateReportService.Properties.Settings>
            <setting name="Path" serializeAs="String">
                <value>C:\1</value>
            </setting>
            <setting name="Branch" serializeAs="String">
                <value>200</value>
            </setting>
            <setting name="b204" serializeAs="String">
                <value>192.168.1.55</value>
            </setting>
            <setting name="b200" serializeAs="String">
                <value>192.168.0.83</value>
            </setting>
            <setting name="Hour" serializeAs="String">
                <value>11</value>
            </setting>
        </UpdateReportService.Properties.Settings>
    </applicationSettings>
</configuration>

And I'd like to change some values to values typed by user during install program.

I find example on VB and try convert it to c#:

namespace InstallConfigurator
{
    [RunInstaller(true)]
    public class SettingsClass : Installer
    {
        public override void Install(System.Collections.IDictionary stateSaver)
        {
            Configuration config = ConfigurationManager.OpenExeConfiguration(Context.Parameters["TARGETDIR"].ToString() + "UpdateReportService.exe");

            ClientSettingsSection applicationSettingsSection = (ClientSettingsSection)config.SectionGroups["applicationSettings"].Sections["UpdateReportService.Properties.Settings"];

            SettingElement Elem = applicationSettingsSection.Settings["Branch"];

            applicationSettingsSection.Settings.Remove(Elem);


            Elem.Value.ValueXml.InnerXml = "30000";
            applicationSettingsSection.Settings.Add(Elem);

            config.Save(ConfigurationSaveMode.Full);
        }
    }
}

But get error "inaccessible due to its protection level" at this place:

SettingElement Elem = applicationSettingsSection.Settings["Branch"];

So, is it possible on c# to access to section in App.config and to change it.

---

Upd. 2012.02.10

i've solved problem this way:

namespace InstallConfigurator
{
    [RunInstaller(true)]
    public class SettingsClass : Installer
    {
        public override void Install(System.Collections.IDictionary stateSaver)
        {
            string xml = Context.Parameters["TARGETDIR"].ToString() + "UpdateReportService.exe.config";

            XmlDocument document = new XmlDocument();
            document.Load(xml);
            XPathNavigator navigator = document.CreateNavigator();
            XmlNamespaceManager ns = new XmlNamespaceManager(navigator.NameTable);

            foreach (XPathNavigator nav in navigator.Select(@"/configuration/applicationSettings/UpdateReportService.Properties.Settings/setting[@name='Branch']/value"))
            {
                nav.SetValue(Context.Parameters["BRANCH"].ToString());
            }

            foreach (XPathNavigator nav in navigator.Select(@"/configuration/applicationSettings/UpdateReportService.Properties.Settings/setting[@name='Path']/value"))
            {
                nav.SetValue(Context.Parameters["PATH"].ToString());
            }

            document.Save(xml);
        }
    }
}

Answer 1

In a similar project, I'm doing it in a slightly different way:

1. Ship your setup with no "myapp.exe.config" file.
2. Instead, ship a "myapp.exe.config.default" file that contains placeholders like "{Branch}".
3. During setup, load the "myapp.exe.config.default" as a string into memory.
4. Replace the placeholders with the actual values (e.g. your "30000").
5. Write the replaced string as the actual file "myapp.exe.config".
6. Bonus: Before writing the config check whether any existing config file is present and copy it as a backup to keep the previous version.

This runs pretty smooth in our applications.