C#•7mo ago

WPF Custom controls/User controls binding issues and total confusion

need to create a reusable WPF control for displaying plugin settings. There is a defined set of settings, e.g., toggle, combo, file path. Each of those settings requires its own WPF control. My initial attempt was to create a User Control, and define a Dependency Property within it:

  public static readonly DependencyProperty SelectedNodeProperty =
    DependencyProperty.Register(
      nameof(SelectedNode),  // XAML attribute name
      typeof(NodeViewModel), // Binding expected type
      typeof(NodeSettings)); // Control name

  public NodeViewModel SelectedNode
  {
    get => (NodeViewModel)GetValue(SelectedNodeProperty);
    set => SetValue(SelectedNodeProperty, value);
  }

  public static readonly DependencyProperty SelectedNodeProperty =
    DependencyProperty.Register(
      nameof(SelectedNode),  // XAML attribute name
      typeof(NodeViewModel), // Binding expected type
      typeof(NodeSettings)); // Control name

  public NodeViewModel SelectedNode
  {
    get => (NodeViewModel)GetValue(SelectedNodeProperty);
    set => SetValue(SelectedNodeProperty, value);
  }

I set the data context in the constructor to this Initially, I've tried using IEnumerable as a type, but let's stay with this non-collection type for now. The view of the User control is:

  <ItemsControl ItemsSource="{Binding SelectedNode.Settings, Mode=OneWay}">
    <ItemsControl.ItemsPanel>
      <ItemsPanelTemplate>
        <StackPanel />
      </ItemsPanelTemplate>
    </ItemsControl.ItemsPanel>
    <ItemsControl.ItemContainerStyle>
      <Style>
        <Setter Property="Control.Template">
          <Setter.Value>
            <ControlTemplate TargetType="UserControl">
              <StackPanel Margin="0,5,0,5">
                <TextBlock Text="Bobek" />
                <ContentPresenter />
              </StackPanel>
            </ControlTemplate>
          </Setter.Value>
        </Setter>
      </Style>
    </ItemsControl.ItemContainerStyle>
    <ItemsControl.Resources>
      <DataTemplate DataType="{x:Type nodeSettings:ToggleSetting}">
        <local:ToggleSettingView Setting="{Binding}" />
      </DataTemplate>
    </ItemsControl.Resources>
  </ItemsControl>

  <ItemsControl ItemsSource="{Binding SelectedNode.Settings, Mode=OneWay}">
    <ItemsControl.ItemsPanel>
      <ItemsPanelTemplate>
        <StackPanel />
      </ItemsPanelTemplate>
    </ItemsControl.ItemsPanel>
    <ItemsControl.ItemContainerStyle>
      <Style>
        <Setter Property="Control.Template">
          <Setter.Value>
            <ControlTemplate TargetType="UserControl">
              <StackPanel Margin="0,5,0,5">
                <TextBlock Text="Bobek" />
                <ContentPresenter />
              </StackPanel>
            </ControlTemplate>
          </Setter.Value>
        </Setter>
      </Style>
    </ItemsControl.ItemContainerStyle>
    <ItemsControl.Resources>
      <DataTemplate DataType="{x:Type nodeSettings:ToggleSetting}">
        <local:ToggleSettingView Setting="{Binding}" />
      </DataTemplate>
    </ItemsControl.Resources>
  </ItemsControl>

I place my control into my MainWindow.xaml:

<controls:NodeSettings SelectedNode="{Binding SelectedNode, Mode=OneWay}" Grid.Column="1" />

<controls:NodeSettings SelectedNode="{Binding SelectedNode, Mode=OneWay}" Grid.Column="1" />

But the data is not bound!!!

1 Reply

Denis•7mo ago

The MainWindow has its data context set to a ViewModel utilizing CommunityToolkit MVVM.

public sealed partial class MainWindowViewModel
  : ObservableObject, IEditorViewModel
{
  [ObservableProperty] private NodeViewModel? m_selectedNode;
  ...
}

public sealed partial class MainWindowViewModel
  : ObservableObject, IEditorViewModel
{
  [ObservableProperty] private NodeViewModel? m_selectedNode;
  ...
}

But here's the kicker... when I go back to the MainWindow.xaml, and modify the binding to:

<controls:NodeSettings SelectedNode="{Binding DataContext.SelectedNode, Mode=OneWay, ElementName=Root}" Grid.Column="1" />

<controls:NodeSettings SelectedNode="{Binding DataContext.SelectedNode, Mode=OneWay, ElementName=Root}" Grid.Column="1" />

where Root is the x:Name of the UserControl. What in the world is going on???

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WPF Custom controls/User controls binding issues and total confusion