Managing mandatory fields with triggers

Question

I would like to set mandatory field backgrounds are red and others are green. So I try to implement below. But I could not control ValueConstraint Nullable property with trigger. Could you help please ?

<Window x:Class="TriggerGirilmesigerekenalanlar.Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:y="http://infragistics.com/Editors"
    Title="Window1" Height="300" Width="300">
    <Window.Resources>
        <Style TargetType="{x:Type y:XamTextEditor}">
            <Style.Triggers>
                <Trigger Property="ValueConstraint" Value="{x:Null}">
                    <Trigger.Setters>
                        <Setter Property="Background" Value="green"></Setter>
                    </Trigger.Setters>
                </Trigger>
                <Trigger Property="y:ValueConstraint.Nullable" Value="false">
                    <Trigger.Setters>
                        <Setter Property="Background" Value="red"></Setter>
                    </Trigger.Setters>
                </Trigger>
            </Style.Triggers>
        </Style>
    </Window.Resources>
    <StackPanel>
        <y:XamTextEditor>
            <y:XamTextEditor.ValueConstraint>
                <y:ValueConstraint Nullable="False" ></y:ValueConstraint>
            </y:XamTextEditor.ValueConstraint>
        </y:XamTextEditor>
        <y:XamTextEditor></y:XamTextEditor>
    </StackPanel>
</Window>

Answer 1

Try this:

<Style.Triggers>
    <Trigger Property="ValueConstraint.Nullable" Value="{x:Null}">
        <Trigger.Setters>
            <Setter Property="Background" Value="Green"></Setter>
        </Trigger.Setters>
    </Trigger>
    <Trigger Property="ValueConstraint.Nullable" Value="false">
        <Trigger.Setters>
            <Setter Property="Background" Value="Red"></Setter>
        </Trigger.Setters>
    </Trigger>
</Style.Triggers>

Answer 2

Actually it gives error.

Error 1 Cannot resolve the Style Property 'Nullable'. Verify that the owning type is the Style's TargetType, or use Class.Property syntax to specify the Property. Line 15 Position 26. D:\Deneme proje\TriggerGirilmesigerekenalanlar\Window1.xaml 15 26 TriggerGirilmesigerekenalanlar

Answer 3

This is the answer.

  <Style TargetType="{x:Type y:XamTextEditor}">
            <Style.Triggers>
                <MultiDataTrigger>
                    <MultiDataTrigger.Conditions>
                        <Condition Binding="{Binding Path=ValueConstraint.Nullable, RelativeSource={RelativeSource Self}}" Value="false" />
                        <Condition Binding="{Binding Path=IsReadOnly, RelativeSource={RelativeSource Self}}" Value="false" />
                        <Condition Binding="{Binding Path=IsEnabled, RelativeSource={RelativeSource Self}}" Value="true" />
                        <Condition Binding="{Binding Path=Visibility, RelativeSource={RelativeSource Self}}" Value="Visible" />
                    </MultiDataTrigger.Conditions>
                    <Setter Property="Background" Value="red"></Setter>
                </MultiDataTrigger>
            </Style.Triggers>
        </Style>