Is it a bug or my mistake?

[GF-Huang]

Why I get this error? But application runnable, shows 3 rows in DataGrid, seems works well.

System.Windows.Data Error: 40 : BindingExpression path error: 'NetworkDataItems' property not found on 'object' 
''RootViewModel' (HashCode=16654654)'. BindingExpression:Path=NetworkDataItems; DataItem='RootViewModel' 
(HashCode=16654654); target element is 'DataGrid' (Name=''); target property is 'ItemsSource' (type 'IEnumerable')

RootViewModel.cs

RootView.xaml

NetworkDataViewModel.cs

NetworkDataView.xaml

[canton7]

In Stylet, you use s:View.Model with ContentControl:

<ContentControl s:View.Model="{Binding NetworkDataViewModel}"/>

You're trying to use it with local:NetworkDataView, but it won't do anything in that case. So the DataContext of NetworkDataView is still set to RootViewModel, which is why you get your binding error.

[GF-Huang]

So I need to wrap local:NetworkDataView into ContentControl as its Content?

[canton7]

No. The entire point of s:View.Model is that it:

1. Takes the ViewModel you gave it (through the binding)
2. Finds the right View type
3. Instantiates an instance of that view
4. Sets up the view, by assigning its DataContext and ActionTarget
5. Sets the view as the ContentControl's content.

This is all explained in the wiki page I linked you to.

You do not manually specify the view type. Stylet works it out from the ViewModel's type. That is the point of the ViewModel-first approach.

[GF-Huang]

Works! Thank you!

[GF-Huang]

I found that it also works if I modify to this, because TabItem is a subclass of ContentControl:

Is there any potential risk lead to unexpected bugs?

[canton7]

That should be fine. See also https://github.com/canton7/Stylet/wiki/Screens-and-Conductors#conductortcollectiononeactive

[GF-Huang]

Hey @canton7 , I found that <ContentControl s:View.Model="{Binding XxxViewModel}" /> does not supports design time display. Is this by design?

[canton7]

There's simply no way to make it work at design-time unfortunately.

[GF-Huang]

If provide an design time instance like d:DataContext="{d:DesignInstance Type=XXX, IsDesignTimeCreatable=True}", will it works?

[canton7]

Try it