Collapsible 'list' of bound elements in WPF

Question

I have what I thought was a simple requirement, but I'm having difficulty working out how to do it.

I'm binding to an address (Line1, Line2, Line3, Line4 for example)

What I want to do is display

Line1
Line2
Line3
Line4

But if any line is empty or null, I'd like to 'collapse':

Line1
Line3
Line4

I've tried a StackPanel with TextBlocks - but I haven't worked out how to get the TextBlocks to 'disappear' if they're empty.

<StackPanel>
    <TextBlock Text="{Binding Line1}"></TextBlock>
    <TextBlock Text="{Binding Line2}"></TextBlock>
    <TextBlock Text="{Binding Line3}"></TextBlock>
    <TextBlock Text="{Binding Line4}"></TextBlock>
</StackPanel>

I've also tried MultiBinding, but I can't work out how to get a newline in the StringFormat.

<TextBlock>
    <TextBlock.Text>
        <!-- Doesn't work: "System.FormatException" -->
        <MultiBinding StringFormat="{}{1}\n{2}\n{3}\n{4}"> 
            <Binding Path="Line1"/>
            <Binding Path="Line2"/>
            <Binding Path="Line3"/>
            <Binding Path="Line4"/>
        </MultiBinding>
    </TextBlock.Text>
</TextBlock>

Any ideas?

Answer 1

It would be easiest just to aggregate all these properties into another readonly one that you bind to:

<TextBlock Text="{Binding Address}"/>

However, you could also bind the Visibility of each TextBlock:

<TextBlock Text="{Binding Line1}" Visibility="{Binding Line1, Converter={StaticResource TextVisibilityConverter}}"/>

The TextVisibilityConverter would return Visibility.Collapsed if the value is null or empty.

HTH, Kent

Answer 2

This is a bit ugly, but it works. I've defined a style with a trigger that collapses a TextBlock if its Text is an empty string:

<StackPanel>
    <StackPanel.Resources>
        <Style TargetType="{x:Type TextBlock}">
            <Style.Triggers>
                <DataTrigger 
                    Binding="{Binding Text,RelativeSource={RelativeSource Self}}" 
                    Value="">
                    <Setter Property="Visibility" Value="Collapsed" />
                </DataTrigger>
            </Style.Triggers>
        </Style>
    </StackPanel.Resources>
    <TextBlock Text="{Binding Line1}" />
    <TextBlock Text="{Binding Line2}" />
    <TextBlock Text="{Binding Line3}" />
    <TextBlock Text="{Binding Line4}" />
</StackPanel>