Question

Folks,

I’m having an interesting issue with Silverlight DataGrid data binding. It may be b/c I’m not binding the data source properly. Here’s the object & the observable collection

/// <summary>
/// Interface for all model elements
/// </summary>
public interface IBaseModel
{

}


/// <summary>
/// Employee model
/// </summary>
public class EmployeeModel : IBaseModel
{       

    public string FirstName { get; set; }
    public string LastName { get; set; }

    public override string ToString()
    {
        return FirstName + LastName;
    }
}


// The observable collection is loaded and bound in the user control
public partial class EmployeeMasterDetailsWindow : UserControl
{
    public EmployeeMasterDetailsWindow()
    {

        try
        {
            InitializeComponent();
            ObservableCollection<IBaseModel> k = new ObservableCollection<IBaseModel>() 
                {new EmployeeModel(){FirstName="Frodo", 
                               LastName=" Baggins"}, 
                new EmployeeModel(){FirstName="Pippin", 
                               LastName="Thomas"}, 
                new EmployeeModel(){FirstName="John", 
                               LastName="Doe"}, 
                new EmployeeModel(){FirstName="Tim", 
                               LastName="Kiriev"}}; 

            dataGrid1.DataContext = k;
            CustomersListBox.DataContext = k;

        }
        catch (Exception ex)
        {


        }

    }
}



//here's the XAML
<UserControl x:Class="AdventureWorksManagement.UI.EmployeeMasterDetailsWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d"
d:DesignHeight="379" d:DesignWidth="516"
         xmlns:sdk="http://schemas.microsoft.com/winfx/2006/xaml/presentation/sdk"
         xmlns:toolkit="http://schemas.microsoft.com/winfx/2006/xaml/presentation/toolkit">


<UserControl.Resources>       

    <DataTemplate x:Key="CustomerTemplate">
        <StackPanel Orientation="Horizontal">
            <TextBlock Text="{Binding FirstName}" />
            <TextBlock Text=" " />
            <TextBlock Text="{Binding LastName}" />
        </StackPanel>
    </DataTemplate>
</UserControl.Resources>

<Grid x:Name="LayoutRoot" Background="White" Height="371" Width="595">
    <Grid.ColumnDefinitions>
        <ColumnDefinition Width="312*" />
        <ColumnDefinition Width="283*" />
    </Grid.ColumnDefinitions>

    <sdk:DataGrid Height="325" HorizontalAlignment="Left"
                  Margin="12,12,0,0" Name="dataGrid1" VerticalAlignment="Top" Width="271" ItemsSource="{Binding}"
                  RowDetailsTemplate="{StaticResource CustomerTemplate}">

    </sdk:DataGrid>
           <ListBox x:Name="CustomersListBox"
             Margin="10,10,10,11"
             ItemsSource="{Binding}"
             ItemTemplate="{StaticResource CustomerTemplate}" />
</Grid>

The Listbox shows all the of the employees, but the DataGrid doesn’t. I don’t even see the DataGrid. I see this error message in the output window:

‘System.Collections.ObjectModel.ObservableCollection1[AdventureWorksManagement.Model.IBaseModel]'
'System.Collections.ObjectModel.ObservableCollection1[AdventureWorksManagement.Model.IBaseModel]’
(HashCode=54025633).
BindingExpression: Path=’FirstName’
DataItem=’System.Collections.ObjectModel.ObservableCollection`1[AdventureWorksManagement.Model.IBaseModel]’
(HashCode=54025633); target element is
‘System.Windows.Controls.TextBlock’
(Name=”); target property is ‘Text’
(type ‘System.String’)..

What could I be doing wrong?

Answer 1

By making it an ObservableCollection<IBaseModel> you are effectively casting all the child objects to IBaseModel, which has no members.

In this instance make it an ObservableCollection<EmployeeModel>.