My FolderBrowserDialog in WPF isn't displayed

Question

I use WPF and want to show a FolderBrowserDialog therefore I have created a WPF-UserControl shell:

<UserControl x:Class="FolderBrowserDialog"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
</UserControl>

and it's code-behind:

    public static readonly DependencyProperty ShowDialogProperty =
        DependencyProperty.Register("ShowDialog", typeof (bool),
            typeof (SaveFileDialog));

    public bool ShowDialog
    {
        get { return (bool) GetValue(ShowDialogProperty); }
        set
        {
            SetValue(ShowDialogProperty, value);
            if (value)
            {
                var folderBrowserDialog = new FolderBrowserDialog();
                if (folderBrowserDialog.ShowDialog() == DialogResult.OK)
                {
                    PathToFolder = folderBrowserDialog.SelectedPath;
                }
            }
        }
    }

I use my FolderBrowser-UserControl on another WPF UserControl where I need this dialog:

<UserControl:FolderBrowserDialogShowDialog="{Binding ShowFolderBrowser, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"/>

On my ViewModel is a public property ShowFolderBrowser with the onPropertyChanged event but the dialog isn't displayed.

I also have not any binding errors in the output panel...

Answer 1

When you use a Property Dependency you shouldn't put code in get and set. The SetValue is called automatically if you set the value from Xaml.

Instead you can use a callback for notification, something like

public static readonly DependencyProperty ShowDialogProperty =
        DependencyProperty.Register("ShowDialog", typeof (bool),
            typeof (SaveFileDialog), new UIPropertyMetadata(false, ShowDialogChangedCallback));

private static void ShowDialogChangedCallback(DependencyObject source, 
        DependencyPropertyChangedEventArgs e)
{
    YourControl control = source as YourControl;
    bool showdialog = (bool)e.NewValue;
    // logic here
}

Further check your dependency property declaration because typeof (SaveFileDialog) can ben wrong, but maybe you have mispelled some name in this example.