CODEWITHSUNDEEP
wpfxamldatatemplate
J23
J23

Reputation: 3221

Hiding A Specific-Indexed Element In An ItemsControl's ItemTemplate

In my WPF/MVVM app, I've got a ListBox with an ItemTemplate; I'm trying to figure out a way to hide a particular element in the template, only for the 0th item in the list. First, some simplified boilerplate:

<ListBox ItemsSource="{Binding MyItems}" AlternationCount="999999" >
    <ListBox.ItemTemplate>
        <DataTemplate>
            <Grid>
                <Grid.ColumnDefinitions>
                    <ColumnDefinition Width="*" />
                    <ColumnDefinition Width="*" />
                </Grid.ColumnDefinitions>

                <TextBlock Grid.Column="0" Text="{Binding Path=(ItemsControl.AlternationIndex), RelativeSource={RelativeSource AncestorType=ListBoxItem}, StringFormat='{}{0}: '}" />
                <TextBlock Grid.Column="1" Text="{Binding Name}" />
            </Grid>
        </DataTemplate>
    </ListBox.ItemTemplate>
</ListBox>

Now let's say I want to hide the "Name" for just the 0th item. As I'd ideally hoped to do this entirely in XAML, I was attempting to leverage an extremely handy extension I often use, CalcBinding, which lets you write calculated binding expressions in XAML (note: it automatically converts between boolean & visibility for you):

<Button Content="Cancel" Command="{Binding CancelCommand}" Visibility="{c:Binding 'ProgressPercent > 0'}"/>

So in this case, I'd thought of something like:

<a:EnumEditBox Visibility="{c:Binding Path='(ItemsControl.AlternationIndex) == 0', RelativeSource={RelativeSource AncestorType=ListBoxItem}}" />

However, this and all other attempts seem to yield errors. In this case, the error is: BindingExpression path error: 'ItemsControl' property not found on 'object' ''ListBoxItem' (Name='')'. BindingExpression:Path=ItemsControl.AlternationIndex; DataItem='ListBoxItem' (Name=''); target element is 'EnumEditBox' (Name=''); target property is 'Visibility' (type 'Visibility')

So my questions are:

  1. Is it possible to do what I'm attempting, solely in XAML?
  2. If not, how might I otherwise accomplish this (to hide an element for the 0-indexed item in a ListBox)?

Any pointers would be greatly appreciated :)

Upvotes: 1

Views: 259

Answers (1)

Clemens
Clemens

Reputation: 128060

The element in the ItemTemplate could have a Style with a DataTrigger on the AlternationIndex property:

<ListBox.ItemTemplate>
    <DataTemplate>
        <Grid>
            ...
            <TextBlock Text="{Binding Name}">
                <TextBlock.Style>
                    <Style TargetType="TextBlock">
                        <Style.Triggers>
                            <DataTrigger
                                Binding="{Binding Path=(ItemsControl.AlternationIndex),
                                          RelativeSource={RelativeSource AncestorType=ListBoxItem}}"
                                Value="0">
                                <Setter Property="Visibility" Value="Collapsed"/>
                            </DataTrigger>
                        </Style.Triggers>
                    </Style>
                </TextBlock.Style>
            </TextBlock>
        </StackPanel>
    </DataTemplate>
</ListBox.ItemTemplate>

Upvotes: 3

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