Datacontext conflicts

by

In a UserControl like this you should never exlicitly set the DataContext to this or anyting else, because the DataContext is usually set externally when you use the UserControl somewhere in your application. The externally applied DataContext is typically (part of) the application’s view model.

You should instead change your internal bindings so that they use an explicit RelativeSource:

<TextBlock
    Text="{Binding Path=Watermark,
                   RelativeSource={RelativeSource AncestorType=UserControl},
                   FallbackValue=This prompt dissappears as you type...}"
    Visibility="{Binding ElementName=txtUserEntry,
                         Path=Text.IsEmpty,
                         Converter={StaticResource BooleanToVisibilityConverter}}" />
<TextBox
    Name="txtUserEntry"
    Text="{Binding Path=Text,
                   UpdateSourceTrigger=PropertyChanged,
                   RelativeSource={RelativeSource AncestorType=UserControl}}" />

and then remove any DataContext assignment from the UserControl’s constructor.

See e.g. this answer (and many other similar) that discuss this topic in detail.

More Related Contents:

  1. WPF Error: Cannot find governing FrameworkElement for target element
  2. How to bind multiple values to a single WPF TextBlock?
  3. WPF Databinding: How do I access the “parent” data context?
  4. RelativeSource binding from a ToolTip or ContextMenu
  5. How to preserve control state within tab items in a TabControl
  6. How can I move a WPF Popup when its anchor element moves?
  7. WPF ContextMenu woes: How do I set the DataContext of the ContextMenu?
  8. DataTrigger where value is NOT null?
  9. Are “{Binding Path=.}” and “{Binding}” really equal
  10. Set value to null in WPF binding
  11. WPF Binding to local variable
  12. WPF: Bind DataGrid to List
  13. Binding errors not showing on output window
  14. WPF Treeview Databinding Hierarchal Data with mixed types
  15. WPF StringFormat on Label Content
  16. WPF StringFormat={0:C} showing as dollars
  17. Bind an element to two sources
  18. TextBox and default Button binding does update too late
  19. Difference between {Binding PropertyName} and {Binding Path=PropertyName}
  20. Binding String Property in Code-Behind TextBlock
  21. Problem binding DataGridComboBoxColumn.ItemsSource
  22. Binding to DateTime.Now. Update the value
  23. A TwoWay or OneWayToSource binding cannot work on the read-only property
  24. WPF binding with StringFormat doesn’t work on ToolTips
  25. Handling null when binding to an Image in XAML
  26. Binding ElementName. Does it use Visual Tree or Logical Tree
  27. Setting DataContext within UserControl is affecting bindings in parent
  28. ItemsControl ItemTemplate Binding
  29. WPF DataGrid : CanContentScroll property causing odd behavior
  30. WPF ViewModel Commands CanExecute issue

Leave a Comment