I'm trying to get images to display in a WPF ListView styled like a WrapPanel as described in this old ATC Avalon Team article: How to Create a Custom View.
When I try to populate the ListView with a LINQ-to-Entities queried collection of ADO.NET Entity Framework objects I get the following exception:
Exception
Items collection must be empty before using ItemsSource.
My code…
Visual Basic
Private Sub Window1_Loaded(...) Handles MyBase.Loaded
ListViewImages.ItemsSource = From g In db.Graphic _
Order By g.DateAdded Ascending _
Select g
End Sub
XAML
<ListView Name="ListViewImages"
SelectionMode="Single"
ItemsSource="{Binding}">
<local:ImageView />
</ListView>
I put a breakpoint on that line. ListViewImages.ItemsSource
is Nothing
just before the LINQ assignment.
I had this same error for a while in a slightly different scenario. I had
<wpftoolkit:DataGrid
AutoGenerateColumns="False"
ItemsSource="{Binding Path=Accounts}" >
<wpftoolkit:DataGridTextColumn
Header="Account Name"
Binding="{Binding Path=AccountName}" />
</wpftoolkit:DataGrid>
which I fixed to be
<wpftoolkit:DataGrid
AutoGenerateColumns="False"
ItemsSource="{Binding Path=Accounts}" >
<wpftoolkit:DataGrid.Columns>
<wpftoolkit:DataGridTextColumn
Header="Account Name"
Binding="{Binding Path=AccountName}" />
</wpftoolkit:DataGrid.Columns>
</wpftoolkit:DataGrid>