Question

I’m trying to create a custom TabItem that is dynamically added to a TabControl defined in a WPF Window. My custom control has an object that contains data I want to bind to specific parts of the template.

<Style TargetType="{x:Type local:EntityTabItem}">
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="{x:Type local:EntityTabItem}">
                <Border>
                    <Grid>
                        <Border x:Name="borderTop" Background="{TemplateBinding Background}" BorderBrush="{TemplateBinding BorderBrush}"/>
                        <StackPanel Orientation="Horizontal" Margin="0,0,2,0">
                            <!-- Want to bind the FileName to this TextBlock -->
                            <TextBlock VerticalAlignment="Center" Text="{Binding Path=Entity.FileName}" Margin="-1,0,0,0" Padding="6,1,10,1"/>
                            <Button x:Name="closeButton" VerticalAlignment="Center" Content="X" Style="{StaticResource TabCloseButton}"/>
                        </StackPanel>
                    </Grid>
                </Border>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
    <Setter Property="ContentTemplate">
        <Setter.Value>
            <DataTemplate>
                <Grid Background="White">
                    <!-- Want to bind the FileText to this TextBox -->
                    <TextBox Margin="15,0,0,0" BorderBrush="{x:Null}" Text="{Binding Path=Entity.FileText}"/>
                </Grid>
            </DataTemplate>
        </Setter.Value>
    </Setter>
</Style>

This is the custom control CS file:

public class EntityTabItem : TabItem
{
    public Entity MyEntity { get; set; }

    public EntityTabItem(string path)
    {
        this.MyEntity = new Entity(path);
    }

    static EntityTabItem()
    {
        DefaultStyleKeyProperty.OverrideMetadata(typeof(EntityTabItem), new FrameworkPropertyMetadata(typeof(EntityTabItem)));
    }
}

I’m fairly certain I need to setup a DataBinding/Source somewhere, but I can’t figure out where to bind it for the bindings in my TextBlock to work.

I honestly cannot wrap my head around DataBinding at all. Half the time, I get it to work just fine without realizing how, and the other half of the time it doesn’t do anything.

I tried also implementing the “Entity” object as a DependencyProperty, but could not get that to work either. As I’m only creating my custom TabItem in CS (never used directly in XAML), does this even matter?

Answer 1

Try using DataContext property, for example like this:

<Style TargetType="{x:Type local:EntityTabItem}">
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="{x:Type local:EntityTabItem}">
                <Border>
                    <Grid>
                        <Border x:Name="borderTop" Background="{TemplateBinding Background}" BorderBrush="{TemplateBinding BorderBrush}"/>
                        <StackPanel Orientation="Horizontal" Margin="0,0,2,0">
                            <!-- Want to bind the FileName to this TextBlock -->
                            <TextBlock VerticalAlignment="Center" Text="{Binding Path=FileName}" Margin="-1,0,0,0" Padding="6,1,10,1"/>
                            <Button x:Name="closeButton" VerticalAlignment="Center" Content="X" Style="{StaticResource TabCloseButton}"/>
                        </StackPanel>
                    </Grid>
                </Border>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
    <Setter Property="ContentTemplate">
        <Setter.Value>
            <DataTemplate>
                <Grid Background="White">
                    <!-- Want to bind the FileText to this TextBox -->
                    <TextBox Margin="15,0,0,0" BorderBrush="{x:Null}" Text="{Binding Path=FileText}"/>
                </Grid>
            </DataTemplate>
        </Setter.Value>
    </Setter>
</Style>


public class EntityTabItem : TabItem
{
    private Entity _myEntity;

    public Entity MyEntity
    {
        get { return _myEntity; }
        set
        {
            _myEntity = value;
            DataContext = value;
        }
    }

    public EntityTabItem(string path)
    {
        this.MyEntity = new Entity(path);
    }

    static EntityTabItem()
    {
        DefaultStyleKeyProperty.OverrideMetadata(typeof(EntityTabItem), new FrameworkPropertyMetadata(typeof(EntityTabItem)));
    }
}