Wednesday, April 28, 2010

Updates to Silverlight Multi-binding support

by StefanOlson via Stefan Olson's Blog on 4/28/2010 10:36:55 AM

Update 29/June/2010: Colin Eberhardt who originally developed this technique has posted an update, including these changes: http://www.scottlogic.co.uk/blog/colin/2010/05/silverlight-multibinding-solution-for-silverlight-4/

The Silverlight multi-binding functionality that I have described previously (see here) doesn't work in Silverlight 4, due to the changes in the xaml parser. This code:

<local:MultiBinding TargetProperty="Text" Converter="{StaticResource TitleConverter}">
    <Binding Path="Surname"/>                            
    <Binding Path="Forename"/>
</local:MultiBinding>

Gives this exception:

System.Windows.Markup.XamlParseException: Set property 'SLMultiBinding.MultiBinding.Bindings' threw an exception

the solution is to wrap the bindings in a binding collection, e.g:

<local:MultiBinding TargetProperty="Text" Converter="{StaticResource TitleConverter}">
    <local:BindingCollection>
        <Binding Path="Surname"/>                            
        <Binding Path="Forename"/>
    </local:BindingCollection>
</local:MultiBinding>