How to display "No Items" content in ComboBox if target ItemsSource is null?

Question

I am trying to create a Combobox with updatable collection. Than I would to display special content inside combobox if collection which binding to combobox in null.

I had try to set TargetNullValue parameter but it's display content not as I expected.

<ComboBox ItemsSource="{Binding MyCollection, UpdateSourceTrigger=PropertyChanged, TargetNullValue='No Items'}"/>

What I Have Now

What I Expect

Answer 1

You may replace the ComboBox's Template when it has no items, e.g. with a TextBlock or any other visual element.

<ComboBox>
    <ComboBox.Style>
        <Style TargetType="ComboBox">
            <Style.Triggers>
                <Trigger Property="HasItems" Value="False">
                    <Setter Property="Template">
                        <Setter.Value>
                            <ControlTemplate TargetType="ComboBox">
                                <TextBlock Text="No Items"/>
                            </ControlTemplate>
                        </Setter.Value>
                    </Setter>
                </Trigger>
            </Style.Triggers>
        </Style>
    </ComboBox.Style>
</ComboBox>