ASP.NET 2.0 has made it pretty nice to create custom configuration sections and be able to access these configuration sections via code. You can basically implement a new ConfigurationSection class. For example, I’ve built a configuration section for my Database Resource Provider like this:

    public class wwDbResourceProviderSection : ConfigurationSection

    {

        [ConfigurationProperty("connectionString",DefaultValue=""),

        Description("The connection string used to connect to the db Resource provider")]      

        public string ConnectionString

        {

            get { return this["connectionString"] as string; }

            set { this["connectionString"]  = value; }

        }

        [ConfigurationProperty("resourceTableName",DefaultValue="Localizations"),

        Description("The name of the table used in the Connection String database for localizations.")]

        public string ResourceTableName

        {

            get { return this["resourceTableName"] as string; }

            set { this["resourceTableName"] = value; }

        }

        [ConfigurationProperty("designTimeVirtualPath",DefaultValue=""),

        Description("The virtual path to the application. This value is used at design time and should be in the format of: /MyVirtual")]

        public string DesignTimeVirtualPath

        {

            get { return this["designTimeVirtualPath"] as string; }

            set { this["designTimeVirtualPath"] = value; }

        }

…

        public wwDbResourceProviderSection(string ConnectionString, string ResourceTableName, string DesignTimeVirtualPath)

        {

            this.ConnectionString = ConnectionString;

            this.DesignTimeVirtualPath = DesignTimeVirtualPath;

            this.ResourceTableName = ResourceTableName;

        }

        public wwDbResourceProviderSection()

        {

        }

    }

And create your ‘properties’ for the section by simply creating public properties and marking them up with a few attributes. The whole thing can then be stuck into web.config like this:

<configSections> 

  <section name="wwDbResourceProvider"

           type="Westwind.Globalization.wwDbResourceProviderSection"

  />

</configSections>  

<wwDbResourceProvider  

    connectionString="server=(local);database=Internationalization;integrated security=true;"

    resourceTableName="Localizations"

    designTimeVirtualPath="/internationalization"

    localizationFormWebPath="~/localizationadmin/localizeform.aspx"

    addMissingResources="false"

    useVsNetResourceNaming="false"

    showLocalizationControlOptions="false"

    showControlIcons="true"

/>

Nice.

However, I’ve not been able to figure out how to write data back to the config file through the ConfigurationSection interface. This class representation supports the ability to save the content, but when I try to assign a value like so:

protected void Page_Load(object sender, EventArgs e)

{

    object T = WebConfigurationManager.GetWebApplicationSection("wwDbResourceProvider") ;

    if (T != null)

    {

        wwDbResourceProviderSection Section = T as wwDbResourceProviderSection;

        Response.Write(Section.ConnectionString);

        Section.ShowControlIcons = false;           

    }

}

I get an exception that the configuration is read only.

Exception Details: System.Configuration.ConfigurationErrorsException: The configuration is read only.

As it turns out the code to write this needs to look a little differently:

protected void Page_Load(object sender, EventArgs e)

{

    Configuration config = WebConfigurationManager.OpenWebConfiguration("~");

    wwDbResourceProviderSection Section = config.GetSection("wwDbResourceProvider") as wwDbResourceProviderSection;

    Section.ShowControlIcons = true;

    config.Save();

    return;

}

And this works…

As long as you’re running at least with High Trust permissions. This understandably fails with Medium trust.