CODEWITHSUNDEEP
wpf
Pavel Voronin
Pavel Voronin

Reputation: 13995

How to make CollectionView grouping respect data template settings

I have ListBox with group style:

<GroupStyle HidesIfEmpty="True" x:Key="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" BorderBrush="#FFA4B97F" BorderThickness="0,0,0,1">
                                    <Expander.Header>
                                        <DockPanel Background="LightSkyBlue" 
                                                           Width="{Binding RelativeSource={RelativeSource  Mode=FindAncestor,  AncestorType={x:Type Expander}},
                                                                           Path=ActualWidth}">
                                            <TextBlock FontWeight="Bold" Text="{Binding Path=Name}" Margin="5,0,0,0" Width="100"/>
                                            <TextBlock FontWeight="Bold" Text="{Binding Path=ItemCount}"/>
                                        </DockPanel>
                                    </Expander.Header>
                                    <Expander.Content>
                                        <ItemsPresenter/>
                                    </Expander.Content>
                                </Expander>
                            </ControlTemplate>
                        </Setter.Value>
                    </Setter>
                </Style>
            </GroupStyle.ContainerStyle>
        </GroupStyle>

Any change in bound collection causes expanders to reopen. Is there any way to remember user preferences and leave expanders folded?

Upvotes: 3

Views: 586

Answers (2)

saragani
saragani

Reputation: 11

The question is what you are doing with the bound collection. I agree with Nikolay that the best option is to have your viewmodel have a property that you will bind the expander to.

As for the question I've asked at the beginning: Are you somewhat refreshing the CollectionView? Refresh causes the UI to be recreated. (Meaning, it is like Reset on an ObservableCollection. It tells the UI to create the user controls and load the XAML of your templates again which is bad for performance).

Upvotes: 1

Nikolay
Nikolay

Reputation: 3828

I can suggest a simple hack - just add IsExpanded property to your model class and bind Expander.IsExpanded to it.

Upvotes: 0

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