CODEWITHSUNDEEP
c#wpfdatagrideventtriggerdatagridcomboboxcolumn
toosensitive
toosensitive

Reputation: 2375

when selected value of a bound combobox column changes, how to change selected values for other columns?

C#, WPF, bound DataGrid Two combobox columns, both bound to some datasources, What I want: When users select an item from one combobox column, the selected value and items list for other combobox column will change automatically. What I saw now, datasource on the second column change, and so does selected value. but UI shows empty as if there is no selection. When I click the second column, the correct selected value will show up. I feel I like an event trigger when the selection of the first combobox changes, inform the second combobox. but not sure how to implement it. thanks

       <dg:DataGrid Grid.Row="1" x:Name="basketDG" Margin="5 0 5 0" Background="White"
              AutoGenerateColumns="False" 
              Style="{StaticResource DataGridStyle}"
              SelectionMode="Extended"
              GridLinesVisibility="None"
              HeadersVisibility="Column" RowDetailsVisibilityMode="VisibleWhenSelected"
              ItemsSource="{Binding BasketItems, Mode=OneWay}" CanUserAddRows="False" CanUserDeleteRows="False"
              SelectionUnit="FullRow" SelectedItem="{Binding SelectedRelComplete}" 
              VerticalScrollBarVisibility="Auto" HorizontalScrollBarVisibility="Auto"
              SelectionChanged="BasketDgSelectionChanged"                  
              Drop="DataGridDrop" 
              DragOver="DataGridDragOver"
              PreviewMouseUp="DGMouseUpEvent"
              AllowDrop="True"
                     ContextMenuOpening="basketDG_ContextMenuOpening"
             >
                <!-- Column definition -->

                 <dg:DataGridComboBoxColumn Width="200" Header="Column" 
                    SelectedValueBinding="{Binding Path=ObjParams.ColumnName, UpdateSourceTrigger=PropertyChanged, 
                    diagnostics:PresentationTraceSources.TraceLevel= High}"
                    DisplayMemberPath="ColName"
                    SelectedValuePath="ColName">
                    <dg:DataGridComboBoxColumn.ElementStyle>
                        <Style TargetType="ComboBox">
                            <Setter Property="ItemsSource" Value="{Binding Obj.Columns}" />
                        </Style>
                    </dg:DataGridComboBoxColumn.ElementStyle>
                    <dg:DataGridComboBoxColumn.EditingElementStyle>
                        <Style TargetType="ComboBox">
                            <Setter Property="ItemsSource" Value="{Binding Obj.Columns}" />
                        </Style>
                    </dg:DataGridComboBoxColumn.EditingElementStyle>
                </dg:DataGridComboBoxColumn>

                <dg:DataGridComboBoxColumn Header="Time Unit" SelectedValueBinding="{Binding ObjParams.TimeUnit}">
                    <dg:DataGridComboBoxColumn.ElementStyle>
                        <Style TargetType="ComboBox">
                            <Setter Property="ItemsSource" Value="{Binding TimeUnitList}" />
                        </Style>
                    </dg:DataGridComboBoxColumn.ElementStyle>
                    <dg:DataGridComboBoxColumn.EditingElementStyle>
                        <Style TargetType="ComboBox">
                            <Setter Property="ItemsSource" Value="{Binding TimeUnitList}" />
                        </Style>
                    </dg:DataGridComboBoxColumn.EditingElementStyle>
                </dg:DataGridComboBoxColumn>

            </dg:DataGrid.Columns>               

        </dg:DataGrid>

Upvotes: 0

Views: 1213

Answers (1)

Xcalibur37
Xcalibur37

Reputation: 2323

Whenever you bind to another element you should use: 

{Binding ElementName=sourceElementName, Path=sourceElementProperty}

Also consider direction. If the source will be the only one doing the updating, then add: 

{Binding ElementName=sourceElementName, Path=sourceElementProperty, Mode=OneWay}

to that bind. Or you can update both directions, use:

{Binding ElementName=sourceElementName, Path=sourceElementProperty, Mode=TwoWay}

If you are looking to utilize pure MVVM, then have both controls bind to the same property, and only permit your source element the Mode=TwoWay privilege.

John Papa says it pretty well.

Data Binding in WPF http://msdn.microsoft.com/en-us/magazine/cc163299.aspx

Upvotes: 0

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