Can I get access from code behind (of a ResourceDictionary) to a named control?

Question

Is it possible to get access from a code behind (of a ResourceDictionary) to a named control?

E.g. for me it is necessary to create lots of folder picking dialogs. A dialog may contain several rows for each folder that has to be chosen. Each row consists of: Label (Name), TextBox (Chosen Path) and a Button (opens FileBrowserDialog).

So now I want to access the TextBox when the FileBrowserDialog is finished. But I can not access the "SelectedFolderTextBox" from CodeBehind.

Is there a better way to achieve what I want to do?

XAML

<ResourceDictionary ...>
    ...

    <StackPanel x:Key="FolderSearchPanel"
                x:Shared="False">
        <Label Content="Foldername"/>
        <TextBox x:Name="SelectedFolderTextBox" 
                 Text="C:\Folder\Path\"/>
        <Button Content="..."
                Click="Button_Click"/>
    </StackPanel>
</ResourceDictionary>

CodeBehind

private void Button_Click(object sender, RoutedEventArgs e)
{
    // Initialize and show
    var dialog = new System.Windows.Forms.FolderBrowserDialog();
    System.Windows.Forms.DialogResult result = dialog.ShowDialog();

    // Process result
    if (result == System.Windows.Forms.DialogResult.OK)
    {
        string selectedPath = dialog.SelectedPath;

        SelectedFolderTextBox.Text = selectedPath;  // THIS DOES NOT WORK
                                                    // since I don't have access to it
                                                    // but describes best, what I want to do
    }
}

Answer 1

when you have a repeated group of controls and a bit of associated functionality it makes sense to create a reusable control:

Add UserControl via project "Add Item" dialog and use this xaml and code:

<UserControl x:Class="WpfDemos.FolderPicker"
             x:Name="folderPicker"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
             mc:Ignorable="d" 
             d:DesignHeight="75" d:DesignWidth="300">
    <StackPanel>
        <Label Content="{Binding Path=Title, ElementName=folderPicker}"/>
        <TextBox x:Name="SelectedFolderTextBox" 
                 Text="{Binding Path=FullPath, ElementName=folderPicker,
                                UpdateSourceTrigger=PropertyChanged}"/>
        <Button Content="..." Click="PickClick"/>
    </StackPanel>
</UserControl>

public partial class FolderPicker : UserControl
{
    public FolderPicker()
    {
        InitializeComponent();
    }

    public static readonly DependencyProperty TitleProperty = DependencyProperty.Register(
        "Title", typeof (string), typeof (FolderPicker), new PropertyMetadata("Folder"));

    public string Title
    {
        get { return (string) GetValue(TitleProperty); }
        set { SetValue(TitleProperty, value); }
    }

    public static readonly DependencyProperty FullPathProperty = DependencyProperty.Register(
        "FullPath", typeof (string), typeof (FolderPicker), new FrameworkPropertyMetadata(@"C:\", FrameworkPropertyMetadataOptions.BindsTwoWayByDefault));

    public string FullPath
    {
        get { return (string) GetValue(FullPathProperty); }
        set { SetValue(FullPathProperty, value); }
    }

    private void PickClick(object sender, RoutedEventArgs e)
    {
        using (var dialog = new System.Windows.Forms.FolderBrowserDialog())
        {
            if (dialog.ShowDialog() == System.Windows.Forms.DialogResult.OK)
                FullPath = dialog.SelectedPath;
        }
    }
}

TextBox is accessible from code-behind. Dependency properties Title and FullPath allows to customize control for different usages and create bindings with a view model (something you can't do with controls group declared as resource). Example

view model:

public class MyViewModel
{
    public string Src { get; set; }
    public string Target { get; set; }
}

view:

public MyWindow()
{
    InitializeComponent();
    this.DataContext = new MyViewModel { Src = "C:", Target = "D:" }
}

<StackPanel>
    <wpfDemos:FolderPicker Title="Source"      FullPath="{Binding Path=Src}"   />
    <wpfDemos:FolderPicker Title="Destination" FullPath="{Binding Path=Target}"/>
</StackPanel>