Get value in app.config - wpf

Question

I have the Key in app.config:
<appSettings>
<add key="SourceWindow" value="C:\Windows" />
</appSettings>
And in MainWindow.xaml have:
<ObjectDataProvider x:Key="keyFiles" MethodName="GetFiles" ObjectType="{x:Type io:Directory}">
<ObjectDataProvider.MethodParameters>
<sys:String> GET VALUE IN APP.CONFIG </sys:String>
</ObjectDataProvider.MethodParameters>
</ObjectDataProvider>
How i can get value in app.config -> <add key="SourceWindow" value="C:\Windows" /> and set this value in <sys:String> VALUE </sys:String>
by xaml?
Any suggestion?

Answer 1

To solve your issue, you can write your own MarkupExtension.
I prepared a short sample code for you. First of all let's see the MarkupExtension class that retrive the app.Config's appSettings:
namespace WpfApplication1
{
public class AppSettingsExtension : MarkupExtension
{
private string key;
public AppSettingsExtension()
{
}
public AppSettingsExtension(string key)
{
Key = key;
}
public string Key
{
get
{
return key;
}
set
{
key = value;
}
}
public override object ProvideValue(IServiceProvider serviceProvider)
{
return ConfigurationManager.AppSettings[Key];
}
}
}
Now it is possible to use the AppSettingsExtension in a XAML (not inside a <sys:String /> node, since it already returns a string object):
<Window x:Class="WpfApplication1.MainWindow" Name="win"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:WpfApplication1"
xmlns:io="clr-namespace:System.IO;assembly=mscorlib"
Title="MainWindow" Height="350" Width="400">
<Window.Resources>
<local:AppSettings Key="SourceWindow" x:Key="str" />
<ObjectDataProvider x:Key="keyFiles" MethodName="GetFiles" ObjectType="{x:Type io:Directory}">
<ObjectDataProvider.MethodParameters>
<local:AppSettings Key="SourceWindow" />
</ObjectDataProvider.MethodParameters>
</ObjectDataProvider>
</Window.Resources>
<StackPanel>
<Label Content="{StaticResource str}" Margin="4" />
<ItemsControl ItemsSource="{Binding Source={StaticResource keyFiles}}" />
</StackPanel>
</Window>
I hope my sample can help you.