Question

My Custom UserControl’s dependency property will bind correctly if the value is statically defined in the XAML calling it, like this:

TextBoxText="myName"

but not if the value is bound dynamically itself:

TextBoxText="{Binding ItemTypeIdCode}"

There is my full Code.

Custom UserControl XAML:

<UserControl
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d"
x:Class="TestUserControl.UserControl1"
DataContext="{Binding RelativeSource={RelativeSource Self}}"
x:Name="UserControl" Height="22" Width="282">

<Grid x:Name="LayoutRoot">
    <TextBlock TextWrapping="Wrap" Text="{Binding MyName, ElementName=LayoutRoot}"/>
</Grid>

Custom UserControl Code:

 public static readonly DependencyProperty TextBoxTextProperty =DependencyProperty.Register("TextBoxText", typeof(string), typeof(UserControl1));

    public string TextBoxText
    {
        get { return (string)GetValue(TextBoxTextProperty); }
        set { SetValue(TextBoxTextProperty, value); }
    }

In my Main Window XAML :

    <Grid x:Name="LayoutRoot">
    <Button Content="Button" Height="78" Margin="0,0,93,112" VerticalAlignment="Bottom" HorizontalAlignment="Right" Width="94" Click="MyButtonClick"/>
    <ListBox x:Name="MyListBox" HorizontalAlignment="Left" Margin="8,8,0,112" Width="192">
        <ListBox.ItemTemplate>
            <DataTemplate>
                <local:UserControl1 HorizontalAlignment="Stretch" Margin="286,37,56,0" VerticalAlignment="Top" d:LayoutOverrides="Height" TextBoxText="{Binding MyName}"/>
            </DataTemplate>
        </ListBox.ItemTemplate>
    </ListBox>
</Grid>

In my Main Window Code :

    private void MyButtonClick(object sender, System.Windows.RoutedEventArgs e)
    {
        List<string> MyName = new List<string>();
        MyName.Add("Name 1");
        MyName.Add("Name 2");
        MyName.Add("Name 3");
        MyListBox.ItemsSource = MyName;
    }

This Code Successfully add my Custom UserControl as ListBoxItem in ListBox But Problem it is not display any text which i Binding.

I don`t understand where i am doing wrong.

Answer 1

You set the DataContext of the UserControl to itself, all bindings will then try to find the path on the UserControl, that is why you should not set the DataContext on UserControls.

You should see a binding error in the Output window of Visual Studio saying something like:

System.Windows.Data Error: 40 : BindingExpression path error: ‘ItemTypeIdCode’ property not found on ‘object’ ”UserControl1′ (Name=’UserControl’)’. …