DataTrigger binding to two controls?

Question

my case should be pretty general. I have a login screen, on which i have an user name textbox, a password box and an OK button.
I want the OK button to be disabled if any of the user name, password text is empty.
I am think to use DataTrigger to achieve this. I have written the following code

<TextBox Height="23" Margin="102,0,12,99" Name="m_edName"
                 VerticalAlignment="Bottom" TabIndex="1" ForceCursor="False" />

<PasswordBox Height="23" Margin="102,0,12,53" Name="m_edPassword"
                     VerticalAlignment="Bottom" TabIndex="2" />

<Button Height="23" Margin="65,0,0,12" Name="okBtn"
                VerticalAlignment="Bottom" Click="okBtn_Click" IsDefault="True"
                TabIndex="3" HorizontalAlignment="Left" Width="75" Content="OK">
            <Button.Style>
                <Style TargetType="Button">
                      <Style.Triggers>
                        <DataTrigger
                              Binding="{Binding ElementName=m_edName, Path=Text}"
                              Value="">
                              <Setter Property="Button.IsEnabled" Value="false" />
                        </DataTrigger>
                        <DataTrigger
                              Binding="{Binding ElementName=m_edPassword, Path=Password}"
                              Value="">
                              <Setter Property="Button.IsEnabled" Value="false" />
                        </DataTrigger>
                    </Style.Triggers>
                </Style>
            </Button.Style>
        </Button>

My problem is that it seems only the user name textbox is working. The OK button will not be disabled if the password box is empty.
Is there a way to specify the relationship between the two DataTriggers? Are they AND relationship or OR relationship?
Thanks
James

Answer 1

I'm guessing it's because PasswordBox.Password (and PasswordBox.SecurePassword) are not dependency properties.

I personally use a Command on the button and in the CanExecute handler of the command is the logic to enable/disable the button.


Mark

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Mark Salsbery Microsoft MVP - Visual C++

Answer 2

Hi,

 

Both SecurePassword and Password properties of PasswordBox are not dependency property. So they will not benefit the change notification.

Mark Salsbery ‘s suggestion  using command in this case is a good clue. Alternatively, you can utilize multi-value converter in this scenario.

 

Hope this helps.

Thanks.

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Jim Zhou -MSFT