Create a DataTemplate for a RadGridViewComboBox Column

Question

instead of using the default telerik gridviewcombobox template, I want to override it and use the wpf original combobox. It works completely fine before trying to apply the datatemplate.

<Telerik:GridViewComboBoxColumn 
    Header="Status" 
    DataMemberBinding="{Binding Status_Id}" 
    ItemsSource="{Binding Statuses, Mode=TwoWay}" 
    DisplayMemberPath="StatusName"  
    SelectedValueMemberPath="Id">
</Telerik:GridViewComboBoxColumn>

When I try to apply the datatemplate, the combo box now displays blank values.

 <Telerik:GridViewComboBoxColumn Header="Status"
    <Telerik:GridViewComboBoxColumn.CellTemplate>
        <DataTemplate>
            <ComboBox SelectedValue="{Binding Status_Id}" 
                      ItemsSource="{Binding Statuses, Mode=TwoWay}" 
                      DisplayMemberPath="StatusName" 
                      SelectedValuePath="Id">
            </ComboBox>
        </DataTemplate>
    </Telerik:GridViewComboBoxColumn.CellTemplate>
</Telerik:GridViewComboBoxColumn>

Am I setting the selected value properties value incorrect? Any assistance would be greatly appreciated. I think when I set the datatemplate, it's hitting the wrong layer. I don't think it's grabbing Statuses from the Viewmodel anymore.

score 3 · Accepted Answer · edited Jun 20 '20 at 09:12

Here is my template I'm using in my projects:

Data Template

                <telerik:GridViewDataColumn Width="150" DataMemberBinding="{Binding Path=StackOptimizerSelectedRule}"
                                        Header="Rules"
                                        IsFilterable="False" IsReorderable="False">
                <telerik:GridViewDataColumn.CellTemplate>
                    <DataTemplate DataType="flowConfiguration:StackOptimizerParameterRuleTreeViewModel">
                        <TextBlock Text="{Binding StackOptimizerSelectedRule, UpdateSourceTrigger=PropertyChanged, Converter={StaticResource EnumTypeConverterKey}}"></TextBlock>
                    </DataTemplate>
                </telerik:GridViewDataColumn.CellTemplate>
                
                <telerik:GridViewDataColumn.CellEditTemplate>
                    <DataTemplate DataType="flowConfiguration:StackOptimizerParameterRuleTreeViewModel">
                        <ComboBox 
                            ItemsSource="{Binding Source={StaticResource StackOptimizerSelectionRules}}"
                            SelectedItem="{Binding StackOptimizerSelectedRule, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}">
                            <ComboBox.ItemTemplate>
                                <DataTemplate DataType="flowConfiguration:StackOptimizerParameterRuleTreeViewModel">
                                    <TextBlock Text="{Binding Converter={StaticResource EnumTypeConverterKey}, UpdateSourceTrigger=PropertyChanged}"/>
                                </DataTemplate>
                            </ComboBox.ItemTemplate>
                        </ComboBox>
                    </DataTemplate>
                </telerik:GridViewDataColumn.CellEditTemplate>
            </telerik:GridViewDataColumn>

Explanations

Here are two templates. The GridViewDataColumn.CellTemplate will be available when containing cell is not in a focus. The CellEditTemplate will be available when a containing cell is in a focus and user change his selection.

Please keep in your mind next things, you have several ways to bound the ItemsSource of the combo:

Regular binding ItemsSource="{Binding SourceCollection, UpdateSourceTrigger=PropertyChanged}". Use this way when your SourceCollection is presenting in the Cell DataContext.
Relative binding ItemsSource="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type PutHereTheTypeOfActualParentThatHoldsDataContextYouNeed}}, Path=DataContext.SourceCollection}". Use this way when your SourceCollection is inside the Parent's data context.
Source from xaml ItemsSource="{Binding Source={StaticResource SourceCollection}}". Use this way when your SourceCollection is static collection Generated in Xaml(for example; based on enum types). You need the next declaration in your <SomeParentVisualAccessibleByridViewDataColumn.Resource> section.

Declaration of source for the third (in addition read the next article)

<ObjectDataProvider x:Key="SourceCollection"
                            MethodName="GetValues"
                            ObjectType="{x:Type flowConfiguration:StackOptimizerSelectionRules}">
        <ObjectDataProvider.MethodParameters>
            <x:Type TypeName="flowConfiguration:StackOptimizerSelectionRules"/>
        </ObjectDataProvider.MethodParameters>
    </ObjectDataProvider>

In my opinion your problem is an incorrect combo's ItemsSource biding, check if you have related binding error exception in your output window. Let me know if you need any help.

Regards.

Create a DataTemplate for a RadGridViewComboBox Column

1 Answers1