I have DataGridComboBoxColumn that is supposed to show integers or text "Default". When I add row the combobox gets correct value from viewmodel's bound property, but when I change value in user interface, the property's set is not called. I tried both SelectedValueBinding and SelectedItemBinding. Converter's ConvertBack is never called. I don't event know should it be called.
Things that work:
- DataGrid SelectedItem binding
- Text column binding both ways (omitted here for shortness)
Here is my code:
XAML:
<DataGrid Name="SelectionSetsGrid" CanUserAddRows="False" CanUserResizeColumns="True" CanUserSortColumns="True"
ItemsSource="{Binding SelectionSets}" AutoGenerateColumns="False"
SelectedItem="{Binding SelectedSelectionSet}">
<DataGrid.Columns>
<DataGridComboBoxColumn Header="Width" SelectedValueBinding="{Binding LineWidthIndex}">
<DataGridComboBoxColumn.ElementStyle>
<Style TargetType="ComboBox" BasedOn="{StaticResource Theme.ComboBox.Style}">
<Setter Property="ItemsSource" Value="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type UserControl}}, Path=DataContext.LineWidths}"/>
<Setter Property="IsReadOnly" Value="True"/>
<Setter Property="ItemTemplate">
<Setter.Value>
<DataTemplate>
<WrapPanel>
<TextBlock Text="{Binding Converter={StaticResource IntToIntTextOrDefaultConverter}}" VerticalAlignment="Center"/>
</WrapPanel>
</DataTemplate>
</Setter.Value>
</Setter>
</Style>
</DataGridComboBoxColumn.ElementStyle>
<DataGridComboBoxColumn.EditingElementStyle>
<Style TargetType="ComboBox" BasedOn="{StaticResource Theme.ComboBox.Style}">
<Setter Property="ItemsSource" Value="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type UserControl}}, Path=DataContext.LineWidths}"/>
<Setter Property="ItemTemplate">
<Setter.Value>
<DataTemplate>
<WrapPanel>
<TextBlock Text="{Binding Converter={StaticResource IntToIntTextOrDefaultConverter}}" VerticalAlignment="Center"/>
</WrapPanel>
</DataTemplate>
</Setter.Value>
</Setter>
</Style>
</DataGridComboBoxColumn.EditingElementStyle>
</DataGridComboBoxColumn>
</DataGrid.Columns>
</DataGrid>
ViewModel (ViewModel implements INotifyPropertyChanged and SetValue raises PropertyChanged):
public class SelectedObjectsViewModel : ViewModel
{
private int[] _lineWidths = { -1, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
public ObservableCollection<int> LineWidths { get; private set; };
private ObservableCollection<SelectionSetViewModel> _selectionSets;
public ObservableCollection<SelectionSetViewModel> SelectionSets
{
get { return _selectionSets; }
set { this.SetValue(ref _selectionSets, value); }
}
private SelectionSetViewModel _selectedSelectionSet;
public SelectionSetViewModel SelectedSelectionSet
{
get { return this._selectedSelectionSet; }
set { this.SetValue(ref _selectedSelectionSet, value); }
}
}
ViewModel for DataGrid row (ViewModel implements INotifyPropertyChanged and SetValue raises PropertyChanged):
public class SelectionSetViewModel : ViewModel
{
public SelectionSetViewModel()
{
LineWidthIndex = -1;
}
private int _lineWidthIndex;
public int LineWidthIndex
{
get { return _lineWidthIndex; }
set { SetValue(ref _lineWidthIndex, value); }
}
Converter:
public class IntToIntTextOrDefaultConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter,
System.Globalization.CultureInfo culture)
{
if ((int)value == -1)
return Fusion.App.Current.Resources["StrDefault"].ToString();
return value.ToString();
}
public object ConvertBack(object value, Type targetType, object parameter,
System.Globalization.CultureInfo culture)
{
return value.Equals(true) ? parameter : Binding.DoNothing;
}
}
<DataGridCheckBoxColumn Header="some header" Binding="{Binding headerBinding}" Width="80">. Changed the names, but hope this helps. – Keyur PATEL