MultiTrigger with the some extra condition on load - wpf

Question

I have a tool window in my application. there are some text input available and i have some validation rule on those text boxes.
say,
validation rule 1
Validation rule 2
validation rule 3
I have a button on that tool window and a style like the bellow
<StackPanel.Resources>
<Style TargetType="{x:Type Button}" BasedOn="{StaticResource ButtonStyle}">
<Style.Triggers>
<MultiDataTrigger>
<MultiDataTrigger.Conditions>
<Condition Binding="{Binding ElementName=HeightTextbox, Path=(Validation.HasError)}" Value="false" />
<Condition Binding="{Binding ElementName=WeightTextBox, Path=(Validation.HasError)}" Value="false" />
<Condition Binding="{Binding ElementName=HeartRateTextBox, Path=(Validation.HasError)}" Value="false" />
</MultiDataTrigger.Conditions>
<Setter Property="IsEnabled" Value="true"/>
</MultiDataTrigger>
</Style.Triggers>
<Setter Property="IsEnabled" Value="false" />
</Style>
</StackPanel.Resources>
and the ok button
<Button Content="Ok" x:Name="OkButton" Height="32" Width="80" Command="{Binding OkCommand}"/>
It is working fine but I want the button to be disabled every time user opens no matters where it is satisfying validation rule or not but the rule should be applied too.

Answer 1

You can try adding some DataTrigger listening to Visibility property using OneTime mode binding and set the IsEnabled to false. This trigger should be placed after your multitrigger so that it can override that trigger:
<Style.Triggers>
<!-- your multi trigger ... -->
<DataTrigger Property="{Binding Visibility,
RelativeSource={RelativeSource Self},
Mode=OneTime}" Value="Visible">
<Setter Property="IsEnabled" Value="false" />
</DataTrigger>
</Style.Triggers>
The above works only when you hide your tool window by calling Close() method, so next time when open the window, it will be loaded first.
If you use something like Hide() method to hide the tool window and open it again using Show(), you can try using the following code instead:
<sys:Boolean x:Key="f">false</sys:Boolean>
<Style.Triggers>
<!-- your multi trigger ... -->
<Trigger Property="Visibility" Value="Visible">
<Setter Property="IsEnabled" Value="{Binding Resources[f],
RelativeSource={RelativeSource AncestorType=StackPanel},
Mode=OneTime}"/>
</Trigger>
</Style.Triggers>
Note about the prefix sys used here, you have to import the namespace System into the XAML code. I hope you know how to do this.