WPF ListView group and sort

Question

I'm trying to group items on my list and sort them from oldest to newest. Grouping works perfect, it just doesn't want to inverse this list.

WPF Code:

            <ListView x:Name="lst_orders" Margin="5" GridViewColumnHeader.Click="results_Click">
            <ListView.Resources>
                <Style TargetType="ListViewItem">
                    <Style.Triggers>
                        <Trigger Property="IsKeyboardFocusWithin" Value="true">
                            <Setter Property="IsSelected" Value="true" />
                        </Trigger>
                    </Style.Triggers>
                </Style>
            </ListView.Resources>
            <ListView.View>
                <GridView>
                    <GridViewColumn>
                        <GridViewColumn.CellTemplate>
                            <DataTemplate>
                                <Button x:Name="goto_parts" Content="Show parts" Width="AUTO" Padding="2" Margin="2" Background="#FF179917" Click="goto_parts_Click"/>
                            </DataTemplate>
                        </GridViewColumn.CellTemplate>
                    </GridViewColumn>
                    <GridViewColumn Header="Order ID" Width="100" DisplayMemberBinding="{Binding fullOrderId}" />
                    <GridViewColumn Header="Job Status" Width="100" DisplayMemberBinding="{Binding status}" />
                    <GridViewColumn Header="Order Type" Width="150" DisplayMemberBinding="{Binding orderType}" />
                    <GridViewColumn Header="Customer Notes" Width="250" DisplayMemberBinding="{Binding notes}" />
                    <GridViewColumn Header="Admin Notes" Width="250" DisplayMemberBinding="{Binding adminNotes}" />
                    <GridViewColumn Header="Production Notes" Width="100" DisplayMemberBinding="{Binding production_notes}" />
                </GridView>
            </ListView.View>
            <ListView.GroupStyle>
                <GroupStyle>
                    <GroupStyle.HeaderTemplate>
                        <DataTemplate>
                            <StackPanel Orientation="Horizontal" Background="Gray">
                                <TextBlock Text="Days: " FontSize="18" FontWeight="Bold"/>
                                <TextBlock Text="{Binding Name}" FontSize="18" FontWeight="Bold"/>
                                <TextBlock Text=" Systems: " FontSize="18" FontWeight="Bold"/>
                                <TextBlock Text="{Binding ItemCount}" FontSize="18" FontWeight="Bold"/>
                            </StackPanel>
                        </DataTemplate>
                    </GroupStyle.HeaderTemplate>
                </GroupStyle>
            </ListView.GroupStyle>
        </ListView>

C# Code:

        ICollectionView view = (CollectionView)CollectionViewSource.GetDefaultView(lst_orders.ItemsSource);
        PropertyGroupDescription groupDescription = new PropertyGroupDescription("daysOld");

        view.GroupDescriptions.Add(groupDescription);
        view.SortDescriptions.Add(new SortDescription("daysOld", ListSortDirection.Descending));

        lst_orders.ItemsSource = view;

daysOld is a property that calculates difference between today's date and order date, works perfect, but I want to see it from the highest number to the lowest. Picture shows what I get, and I want to reverse it.

Answer 1

Your code is correct.I've made a test. It is possible to see in view:

C#:

List<SomeClass> list = new List<SomeClass>();
Random rnd = new Random();
for (int i = 0; i < 10; i++)
{              
   list.Add(new SomeClass() { DaysOld = DateTime.Now.Add(new TimeSpan(0, rnd.Next(25), 0))});
}
ICollectionView view = (CollectionView)CollectionViewSource.GetDefaultView(list);
PropertyGroupDescription groupDescription = new PropertyGroupDescription("daysOld");
view.GroupDescriptions.Add(groupDescription);
view.SortDescriptions.Add(new SortDescription("DaysOld",   ListSortDirection.Descending));
listBox.ItemsSource = view;
listBox.DisplayMemberPath = "DaysOld";

XAML:

<ListBox Name="listBox"/>        

Model:

public class SomeClass
{
    public DateTime DaysOld { get; set; }
}

Image: