Silverlight: Empty Data Grid

Question

I'm trying to fill a DataGrid with an anonymous type generated by a LINQ query. When I put the query results in a list box, it appears fine. However, when I put the query results in a data grid, the correct number of rows are generated, but the cells are empty.

(The data grid is on the left, with the list box on the right.)

Assigning the data source:

testListBox.ItemsSource = debtPerUser.ItemsSource = ExpenseViewModel.getDebtData(username);

The XAML:

<sdk:DataGrid Height="222" HorizontalAlignment="Left" Margin="31,89,0,0" Name="debtPerUser" VerticalAlignment="Top" Width="516" AutoGenerateColumns="True" />
<ListBox Height="222" HorizontalAlignment="Left" Margin="567,89,0,0" Name="testListBox" VerticalAlignment="Top" Width="173" />

What could I be doing wrong here?

getDebtData:

    internal static IEnumerable getDebtData(string username)
    {
        IEnumerable<String> users = getUsersInvolving(username);

        var debt = from user in users
                   select new {
                     User = user,
                     Net = owedBetween(username, user) - owedBetween(user, username)
                   };

        return debt.Where(d => d.Net != 0);
    }

Update: It works when I'm not using an anonymous query type. Perhaps that's the problem?

Answer 1

Without knowing exactly what type of collection the method ExpenseViewModel.getDebtData returns, if it's using LINQ you might have some luck trying ExpenseViewModel.getDebtData(username).ToList()

Answer 2

Yes, anonymous types are designed to be used in the method they're declared in. Exposing them outside can lead to evil outcomes. I would use a strongly typed enumerable in this case.