How to add header to grouped DataGrid? for example i need the number of records without Card? Detailed in the picture.

<Grid>
    <Grid.Resources>
        <CollectionViewSource x:Key="GroupItem" Source="{Binding Items}">
            <CollectionViewSource.GroupDescriptions>
                <PropertyGroupDescription PropertyName="Group" />
            </CollectionViewSource.GroupDescriptions>
        </CollectionViewSource>
    </Grid.Resources>
    
    <DataGrid x:Name="dataGrid1" 
              ItemsSource="{Binding Source={StaticResource GroupItem}}"
              CanUserAddRows="False">
        <DataGrid.GroupStyle>
            <GroupStyle>
                <GroupStyle.ContainerStyle>
                    <Style TargetType="{x:Type GroupItem}">
                        <Setter Property="Margin" Value="0,0,0,5"/>
                        <Setter Property="Template">
                            <Setter.Value>
                                <ControlTemplate TargetType="{x:Type GroupItem}">
                                    <Expander IsExpanded="True" Background="Yellow" >
                                        <Expander.Header>
                                            <StackPanel Orientation="Horizontal">
                                                <TextBlock Text="{Binding Name}" Margin="0,0,20,0"/>
                                                <TextBlock Text="Count:  "/>
                                                <TextBlock Text="{Binding ItemCount}"/>
                                            </StackPanel>
                                        </Expander.Header>
                                        <Expander.Content>
                                            <ItemsPresenter />
                                        </Expander.Content>
                                    </Expander>
                                </ControlTemplate>
                            </Setter.Value>
                        </Setter>
                    </Style>
                </GroupStyle.ContainerStyle>
            </GroupStyle>
        </DataGrid.GroupStyle>
    </DataGrid>
</Grid>

The picture shows everything in detail.

Sorry for my English.

CodePudding user response：

You could use a converter that counts the number of records that satisfy the criteria:

public class NoCardsConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        return (value as IEnumerable<object>)?
            .OfType<YourClass>()
            .Count(x => string.IsNullOrEmpty(x.Card)) ?? 0;
    }

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        throw new NotSupportedException();
    }
}

XAML:

<ControlTemplate TargetType="{x:Type GroupItem}">
    <Expander IsExpanded="True" Background="Yellow" >
        <Expander.Header>
            <StackPanel Orientation="Horizontal">
                <TextBlock Text="{Binding Name}" Margin="0,0,20,0"/>
                <TextBlock Text="Count:  "/>
                <TextBlock Text="{Binding ItemCount}" Margin="0,0,20,0"/>
                <TextBlock Foreground="Red">
                    <Run Text="No cards:" />
                    <Run>
                        <Run.Text>
                            <Binding Path="Items" Mode="OneWay">
                                <Binding.Converter>
                                    <local:NoCardsConverter />
                                </Binding.Converter>
                            </Binding>
                        </Run.Text>
                    </Run>
                </TextBlock>
            </StackPanel>
        </Expander.Header>
        <Expander.Content>
            <ItemsPresenter />
        </Expander.Content>
    </Expander>
</ControlTemplate>