CODEWITHSUNDEEP
c#wpflistviewexpander
user1850936
user1850936

Reputation: 129

Couldn't locate expander in listview

I am having an expander than bind in the listview.

And I have another button to collapse/ expand all expander.

In code behind, I couldn’t locate the expander by using the code: Expander exp = (Expander)listViewResult.FindResource("MyExpander");

Any idea to do so?

<ListView Name="listViewResult" Margin="0,172,-10,-491" BorderBrush="Gray" BorderThickness="1" 
                      TextElement.FontFamily="Segoe UI" TextElement.FontSize="12" 
                      Background="White" 
                      GridViewColumnHeader.Click="GridViewColumnHeaderClickedHandler" >
                <ListView.View>
                    <GridView ColumnHeaderContainerStyle="{StaticResource GridViewColumnHeaderStyle}" >
                      ……
                    </GridView>
                </ListView.View>

                <ListView.GroupStyle>
                    <GroupStyle>
                        <GroupStyle.ContainerStyle>
                            <Style TargetType="{x:Type GroupItem}">
                                <Setter Property="Template">
                                    <Setter.Value>
                                        <ControlTemplate>
                                            <Expander Name="MyExpander" IsExpanded="False">
                                                <Expander.Header>
                                                    <StackPanel Orientation="Horizontal">
                                                        <TextBlock Text="{Binding Name}" FontWeight="Bold" VerticalAlignment="Bottom" />
                                                    </StackPanel>
                                                </Expander.Header>
                                                <ItemsPresenter Margin="20,0,0,0" />
                                                <!--<ItemsPresenter />-->
                                            </Expander>
                                        </ControlTemplate>
                                    </Setter.Value>
                                </Setter>
                            </Style>
                        </GroupStyle.ContainerStyle>
                    </GroupStyle>
                </ListView.GroupStyle>
            </ListView>

Upvotes: 0

Views: 553

Answers (3)

low
low

Reputation: 36

In order to expand/ collapse all expander, you could locate all the expanders by finding all child in the collection

Calling the method:

Collection<Expander> collection = FindVisualChild<Expander>(listViewResult);
foreach (Expander expander in collection)
{
     expander.IsExpanded = true;
}

The Method:

private static Collection<T> FindVisualChild<T>(DependencyObject current) where T : DependencyObject
{
    if (current == null)
    {
        return null;
    }
    var children = new Collection<T>();
    FindVisualChild (current, children);
    return children;
}
private static void FindVisualChild<T>(DependencyObject current, Collection<T> children) where T : DependencyObject
{
    if (current != null)
    {
        if (current.GetType() == typeof(T))
        {   children.Add((T)current);   }
        for (int i = 0; i < System.Windows.Media.VisualTreeHelper.GetChildrenCount(current); i++)
        {
           FindVisualChild (System.Windows.Media.VisualTreeHelper.GetChild(current, i), children);
        }
    }
}

Upvotes: 2

Arushi Agrawal
Arushi Agrawal

Reputation: 629

Try using x:Name property to define name for your expander and below code can help: Expander exp = (Expander)listViewResult.FindName("MyExpander");

Upvotes: 0

jadavparesh06
jadavparesh06

Reputation: 946

Use following method to find the controls within your Visual tree. 

public static Visual GetDescendantByName (Visual element, string name)
         {
             if (element == null) return null;
             if (element is FrameworkElement
                 && (element as FrameworkElement).Name == name) return element;
             Visual result = null;
             if (element is FrameworkElement)
                 (element as FrameworkElement).ApplyTemplate();
             for (int i = 0; i < VisualTreeHelper.GetChildrenCount(element); i++)
             {
                 Visual visual = VisualTreeHelper.GetChild(element, i) as Visual;
                 result = GetDescendantByName(visual, name);
                 if (result != null)
                     break;
             }
             return result;
         }

where element will be your ListView and name will be name of the FrameworkElement you are looking for.

Upvotes: 2

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