Remove white space from MultiBinding StringFormat - wpf

Question

Unable to remove whitespace from StringFormat.
If no 'Type' data the following whitespace doesn't fallback.
ReleaseDate, space, space, dot, space, space, Type, space (some reason it doesn't remove this space), Color
<TextBlock>
<TextBlock.Text>
<MultiBinding StringFormat="{}{0:yyyy} · {1} {2}" >
<Binding Path="ReleaseDate" FallbackValue="{x:Null}"/>
<Binding Path="Type" FallbackValue="{x:Null}"/>
<Binding Path="Color" FallbackValue="{x:Null}"/>
</MultiBinding>
</TextBlock.Text>
</TextBlock>

Answer 1

You may probably replace the MultiBinding and its StringFormat by a DataTrigger:
<TextBlock>
<TextBlock.Style>
<Style TargetType="TextBlock">
<Setter Property="Text">
<Setter.Value>
<MultiBinding StringFormat="{}{0:yyyy} · {1} {2}" >
<Binding Path="ReleaseDate" FallbackValue="{x:Null}"/>
<Binding Path="Type"/>
<Binding Path="Color" FallbackValue="{x:Null}"/>
</MultiBinding>
</Setter.Value>
</Setter>
<Style.Triggers>
<DataTrigger Binding="{Binding Type}" Value="{x:Null}">
<Setter Property="Text">
<Setter.Value>
<MultiBinding StringFormat="{}{0:yyyy} · {1}" >
<Binding Path="ReleaseDate" FallbackValue="{x:Null}"/>
<Binding Path="Color" FallbackValue="{x:Null}"/>
</MultiBinding>
</Setter.Value>
</Setter>
</DataTrigger>
</Style.Triggers>
</Style>
</TextBlock.Style>
</TextBlock>

Answer 2

While the approach with DataTrigger works, it is very verbose. I would make it a two-step process: bind Type separately with a StringFormat which has a space, then bind everything together
<TextBlock Name="Title"
local:Attached.SomeString="{Binding Type,
StringFormat='\{0} ',
TargetNullValue=''}">
<TextBlock.Text>
<MultiBinding StringFormat="{}{0:yyyy} · {1}{2}">
<Binding Path="Login" />
<Binding Path="(local:Attached.SomeString)"
RelativeSource="{RelativeSource Self}" />
<Binding Path="Name" />
</MultiBinding>
</TextBlock.Text>
</TextBlock>
If Type is not null then SomeString binding uses string format, and returns Type + space at the end. If Type is null, then binding return empty string.
SomeString is a reusable attached dependency property without special meaning. It declared as
public class Attached
{
public static readonly DependencyProperty SomeStringProperty =
DependencyProperty.RegisterAttached("SomeString", typeof (string), typeof (Attached));
public static void SetSomeString(UIElement element, string value)
{
element.SetValue(SomeStringProperty, value);
}
public static string GetSomeString(UIElement element)
{
return (string)element.GetValue(SomeStringProperty);
}
}
TextBlock has Tag property which can be used to store (or bind) some data, but Tag is of type object, and doesn't use StringFormat from binding. So I couldn't use Tag for my purpose here, and had to create another property, which has string type. (note also special syntax to bind attached property)