Question

The default Windows 8 project template has a CollectionViewSource in the template.

<CollectionViewSource
       x:Name="itemsViewSource"
       Source="{Binding Model.Invitations}"
       d:Source="{Binding Invitations, Source={d:DesignInstance Type=vm:DesignerFilteredInvitations, IsDesignTimeCreatable=True}}" />

Obviously not all pages have a collection as their model, you can define a DataContext like this:

<vm:MySingleItemViewModel x:Key="Model" />

How do you define the design instance for this kind of model?

Answer 1

Okay, using this works fine:

<Page 
d:DataContext="{d:DesignInstance Type=Models:ViewModel, IsDesignTimeCreatable=True}"

And using this works fine:

<d:Page.DataContext>
    <Models:ViewModel/>
</d:Page.DataContext>

I must tell you the latter is an easier approach, too. It is also what Visual Studio will generate when you setup a data source in the designer. It also gives you fully-typed bindings. But either is acceptable.

Another note. I can see no good reason to set an object directly to the source of a CollectionViewSource. Normally you would be binding the CVS’s Source property to a property inside your ViewModel. But, given your question: Here’s how:

<CollectionViewSource 
    x:Name="TestCVS" Source="{Binding}"
    d:DataContext="{Binding Source={d:DesignInstance Type=Models:ViewModel, IsDesignTimeCreatable=True}}"/>

Binding to the Source in the designer caused me endless trouble. But it irritated me more because I knew I would never do it this way. This is what I wanted to do:

<d:Page.DataContext>
    <Models:ViewModel/>
</d:Page.DataContext>

<Page.Resources>
    <CollectionViewSource x:Name="TestCVS" Source="{Binding}" />
</Page.Resources>

You better have a great reason for your approach!

Best of luck!