Question

I have several ComboBoxes in a DataForm and am trying to have it so that certain ComboBoxes are disabled until a particular ComboBox is selected. To this end, I created a notification property named CanEditCombo in the class that is bound to the DataContext and configured my ComboBoxes like so:

<ComboBox ... IsEnabled="{Binding CanEditCombo, Mode=OneWay}" />

The CanEditCombo is initially false, yet my ComboBoxes are editable when the DataForm first loads.

If I apply the same IsEnabled binding syntax to a TextBox in my DataForm it works as expected: disabled at first but enabled once CanEditCombo becomes true.

Here is an example chunk of XAML:

<toolkit:DataForm CurrentItem="{Binding NewProject, Mode=TwoWay}" x:Name="dfNewProject" CommandButtonsVisibility="None">
    <toolkit:DataForm.EditTemplate>
        <DataTemplate>
            <StackPanel>
                ...

                <toolkit:DataField>
                    <ComboBox ItemsSource="{Binding ProjectOptions, Mode=OneWay}"
                                SelectedValue="{Binding Options, Mode=TwoWay}"
                                DisplayMemberPath="Value"
                                SelectedValuePath="Key"
                                IsEnabled="{Binding CanEditCombo, Mode=OneWay}" />
                </toolkit:DataField>

                ...
            </StackPanel>
        </DataTemplate>
    </toolkit:DataForm.EditTemplate>
</toolkit:DataForm>

What’s more, even if I hard-code the ComboBox’s IsEnabled property to False in the markup above the ComboBox is still editable.

How do I go about having the ComboBox’s IsEnable property set via binding syntax when the ComboBox is in a DataForm?

Answer 1

Not sure if you’ve discovered the answer to this yet, but there’s actually a really simple solution: set IsEnabled on the DataField rather than the ComboBox (or any other DataField nested control).

<toolkit:DataField IsEnabled="{Binding CanEditCombo, Mode=OneWay}">
     <ComboBox ItemsSource="{Binding ProjectOptions, Mode=OneWay}"
               SelectedValue="{Binding Options, Mode=TwoWay}"
               DisplayMemberPath="Value"
               SelectedValuePath="Key" />
</toolkit:DataField>

I’m not sure exactly what the DataField is doing internally but the IsEnabled property never gets accessed on a nested control.