Question

I’m pretty sure this is a UserControl DataContext problem, but I am just not seeing it:

This is my XAML:

<UserControl x:Class="WFT.Controls.DetailsBox"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:wft="clr-namespace:WFT.Controls" >

    <wft:CaptionedBox Caption="Details" Margin="1" >
        <ListView ItemsSource="{Binding Map}">
            <ListView.View>
                <GridView>
                    <GridViewColumn DisplayMemberBinding="{Binding Key}"  />
                    <GridViewColumn DisplayMemberBinding="{Binding Value}" />
                </GridView>
            </ListView.View>
        </ListView>
    </wft:CaptionedBox>
</UserControl>

This is the code-behind:

public partial class DetailsBox : UserControl
{
    ObservableCollection<KeyValuePair<string, string>> m_Map =
        new ObservableCollection<KeyValuePair<string, string>>( );

    public ObservableCollection<KeyValuePair<string, string>> Map
    { get { return m_Map; } }

    public DetailsBox( )
    {
        InitializeComponent( );
        DataContext = this;
    }

    public void Initialize( List<string> map )
    {
        IEnumerable<int> range = Enumerable.Range( 0, map.Count );

        m_Map = new ObservableCollection<KeyValuePair<string, string>>(
            range.Where( r => 0 == r % 2 && map[ r + 1 ].Trim( ) != "N/A" )
            .Select( r => new KeyValuePair<string, string>( map[ r ], map[ r + 1 ] ) ).ToList( ) );

    }
}

At run-time, Map has eight items, but nothing shows in the ListView. In a stand-alone test app, it works with DataContext="{Binding RelativeSource={RelativeSource Self}}", but as a UserControl, that didn’t work. I have even resorted, as you see above, to attempting to set DataContext = this in the constructor.

Thanks!

Answer 1

I never did figure out how to set the DataContext in the XAML, but I got things to work by doing the following:

In the XAML, I added x:Name="listview" to the ListView.

Then, in the code behind, I turned the property, Map, into a DependencyProperty

public ObservableCollection<KeyValuePair<string, string>> Map
{
    get { return (ObservableCollection<KeyValuePair<string, string>>)GetValue( MapProperty ); }
    set { SetValue( MapProperty, value ); }
} 

public static DependencyProperty MapProperty = DependencyProperty.Register( "Map",
     typeof( ObservableCollection<KeyValuePair<string, string>> ), 
     typeof( DetailsBox ),
     new PropertyMetadata( new ObservableCollection<KeyValuePair<string, string>>( ) ) );

removed DataContext = this; from the constructor, and added listview.DataContext = Map; to Initialize, after loading Map.