DataGridComboBoxColumn binding issue

Question

I have DataGridComboBoxColumn in DataGrid:

  <DataGridComboBoxColumn Header="{x:Static Properties:Resources.Unit}" Width="Auto"

                                    SelectedValueBinding="{Binding UnitUnitId}"
                                    SelectedValuePath="UnitId"
                                    DisplayMemberPath="Name" >
                <DataGridComboBoxColumn.ElementStyle>
                    <Style TargetType="ComboBox">
                        <Setter Property="ItemsSource" Value="{Binding Path=DataContext.Units,RelativeSource={RelativeSource AncestorType={x:Type UserControl}}}"/>
                    </Style>
                </DataGridComboBoxColumn.ElementStyle>
                <DataGridComboBoxColumn.EditingElementStyle>
                    <Style TargetType="ComboBox">
                        <Setter Property="ItemsSource" Value="{Binding Path=DataContext.Units,RelativeSource={RelativeSource AncestorType={x:Type UserControl}}}"/>
                    </Style>
                </DataGridComboBoxColumn.EditingElementStyle>

            </DataGridComboBoxColumn>

and ComboBox:

<ComboBox x:Name="unitBox" ItemsSource="{Binding Path=Units}" 
              SelectedItem="{Binding TaxSubGroup.Unit}"
               Grid.Row="2"
              Grid.Column="1" Margin="11,11,0,0" HorizontalAlignment="Stretch">
        <ComboBox.ItemTemplate>
            <DataTemplate>
                <TextBlock Text="{Binding Converter={x:Static c:UnitToStringConverter.Default}}"/>
            </DataTemplate>
        </ComboBox.ItemTemplate>
    </ComboBox>

Units property:

   public ObservableCollection<Unit> Units
    {
        get
        {
            return _units;
        }
        set
        {
            if(_units!=value)
            {
                _units = value;
                RaisePropertyChanged("Units");
            }
        }
    }

when i'm changing ComboBoxes value, DataGridComboBoxColumn's value updating automatically, but changing DataGrid's comboboxcolumn's value not updating ComboBoxes value. Why?

UPDATED

The problem was in DataGridComboBoxCulumn's SelectedValueBinding property. All i needed is to add UpdateSourceTrigger property:

SelectedValueBinding="{Binding UnitUnitId,UpdateSourceTrigger=PropertyChanged}"

WPF-it WPF-it · Accepted Answer · 2011-11-22T08:11:21

Are you updating TaxSubGroup.Unit in the setter of UnitUnitId property?

In your DataContext model class do something similar to this...

 public int UnitUnitId
 {
     get 
     {
         return this.unitID; 
     }
     set 
     {
         this.unitID = value;
         this.TaxSubGroup.Unit = Units.FirstOrDefault(u => u.UnitID == value);
         this.NotifyPropertyChange("UnitUnitId");
     }
 }

This will match SelectedItem of Combobox by reference.

DataGridComboBoxColumn binding issue

1 Answers