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Programmatic access to treeview items

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TreeView

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answered on 19 May 2009, 10:19 AM

treeviewexpandbypath-dispatched.zip

Hello Henrik & Jarred,

You can use the ExpandByPath & SelectByPath methods even now, you just need to dispatch them. Something like this:

    
            treeView.ItemsSource = new object[] { GetTopOrganisation("A") };  
        
            //This will not work:  
        
            //ExpandItemAndSelect();   
        
            //But this will work:  
        
            this.Dispatcher.BeginInvoke(ExpandItemAndSelect);  
        
            //The above is the same as this:  
        
            //this.Dispatcher.BeginInvoke(() => ExpandItemAndSelect());

    
            private void ExpandItemAndSelect()  
        
            {  
        
                var path = "Top Organisation A|Organisation 1.1 A|Organisation 2.1 A|Organisation 3.1 A|Person 3.1.1";  
        
                treeView.ExpandItemByPath(path, "|");  
        
                treeView.GetItemByPath(path, "|").IsSelected = true;  
        
            }

It will also work with databound items.

You can have a look at the attached example,

Hopefully this is what you need,

Best wishes,
Miroslav
the Telerik team

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answered on 20 May 2009, 06:47 AM

Hello Jarred & Henrik,

Yes, the ToString() may now work in all cases and there surely are better uses for it. This is one of the improvements we are thinking about.

As for the ContainerFromItemRecursive, I am afraid that it will really slow down the TreeView at times and I am a bit unsure whether it is a good idea to force the creation of items. The reason for this is that with the path you need only to generate the container of the "branch" of the TreeView that you need. On the other hand to search for a container, you need to start generating containers until you find it (breadth-first or depth-first). At worst, this means generating the containers for all the items just to find one.

Greetings,
Miroslav
the Telerik team

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answered on 20 May 2009, 07:12 AM

Hi Jarred,

Sorry if a my last reply sounded a bit dismissive. I am thinking now of the reasons why you may need the container.

- You want to set a property. Then you can always use the ItemContainerStyle. Even attached properties can be set this way.

- You want to bind a property. Then you can use the not-so-well-promoted-but-still-great feature of all our items controls: the ContainerBinding. You can attach a ContainerBindingCollection to the root element of the ItemTemplate, it will contain bindings that will be applied to the container when it is generated. This way you will not have to manually change things like IsEnabled, IsSelected, etc.

Hopefully this will be helpful :)

Best wishes,
Miroslav
the Telerik team

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answered on 20 May 2009, 08:07 AM

The ContainerBinding stuff looks like a great feature. I wish I had known about it sooner. :) But I'm having a problem. I've done a simple test and successfully managed to bind the IsEnabled, Header and IsSelected properties of the TreeViewItem. But what I really need for my application is to bind the IsChecked property. And that doesn't work. Any ideas?

    
            <UserControl x:Class="TelerikTestProject.Page" 
        
                         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
        
                         xmlns:telerik="clr-namespace:Telerik.Windows.Controls;assembly=Telerik.Windows.Controls" 
        
                         xmlns:telerikinput="clr-namespace:Telerik.Windows.Controls;assembly=Telerik.Windows.Controls.Input" 
        
                         xmlns:teleriknav="clr-namespace:Telerik.Windows.Controls;assembly=Telerik.Windows.Controls.Navigation" 
        
                         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
        
                         Width="400" 
        
                         Height="300"> 
        
                <UserControl.Resources> 
        
                    <telerik:ContainerBindingCollection x:Key="TreeItemContainerBindings"> 
        
                        <telerik:ContainerBinding PropertyName="IsEnabled" 
        
                                                  Binding="{Binding IsSelected}" /> 
        
                        <telerik:ContainerBinding PropertyName="IsSelected" 
        
                                                  Binding="{Binding IsSelected}" /> 
        
                        <telerik:ContainerBinding PropertyName="Header" 
        
                                                  Binding="{Binding Name}" /> 
        
                        <!--Does not work--> 
        
                        <telerik:ContainerBinding PropertyName="IsChecked" 
        
                                                  Binding="{Binding IsSelected}" /> 
        
                    </telerik:ContainerBindingCollection> 
        
                </UserControl.Resources> 
        
                <Grid x:Name="LayoutRoot" 
        
                      Background="White"> 
        
                    <Grid.RowDefinitions> 
        
                        <RowDefinition Height="Auto"></RowDefinition> 
        
                        <RowDefinition Height="Auto"></RowDefinition> 
        
                    </Grid.RowDefinitions> 
        
                    <teleriknav:RadTreeView x:Name="RadTreeView1" 
        
                                            IsOptionElementsEnabled="True" 
        
                                            ItemsOptionListType="CheckList" 
        
                                            SelectionMode="Multiple" 
        
                                            Grid.Row="1"> 
        
                        <teleriknav:RadTreeView.ItemTemplate> 
        
                            <telerik:HierarchicalDataTemplate ItemsSource="{Binding SubTopics}" 
        
                                                              telerik:ContainerBinding.ContainerBindings="{StaticResource TreeItemContainerBindings}"> 
        
                            </telerik:HierarchicalDataTemplate> 
        
                        </teleriknav:RadTreeView.ItemTemplate> 
        
                    </teleriknav:RadTreeView> 
        
                </Grid> 
        
            </UserControl>

The class I'm binding to looks like this:

    
            public class HelpTopic  
        
            { 
        
                public string Name { get; set; } 
        
                public ObservableCollection<HelpTopic> SubTopics { get; set; } 
        
                public  bool? IsSelected { get; set; } 
        
                public HelpTopic() 
        
                { 
        
                } 
        
            }

answered on 08 Jul 2009, 07:32 AM

Miroslav

I have my tree view's LoadOnDemmand enabled and I tried to load child nodes of a specific node (child not loaded yet) programmatically. So I tried your code above to find the node I want to expand (load children) like below code:

private void ExpandItemAndSelect(string path)
    {
        treeView.ExpandItemByPath(path, "|");
        RadTreeViewItem item = treeView.GetItemByPath(path, "|"); // node to expand
        item.IsExpanded = true;      // expand it
    }

I got an error message in my IE left bottom corner and it seems an error from the treeview control itself:

Sys.InvalidOpreationException: ManagedRuntimeError error #4004 in control "Xmal1": System.IndexOutOfRangeException: Index was outside the bounds of the array. at Telerik.Windows.Controls.RadTreeView.RadTreeView_ItemPrepared......

was i doing something wrong?

answered on 09 Jul 2009, 02:06 PM

Hello James,

Sorry for the delayed reply,

I could not figure out the cause of the exception.

Could you provide the full stack trace of the exception?
Also, are you using SL2 or SL3?
Do you see the exception in the sample project as well?

In the Q2 release the GetItemByPath and ExpandItemByPath work in a very similar way, with just one difference: ExpandItemByPath works asynchronously, while GetItemByPath forces layout updates and tries to complete synchronously. Still, even if some of the items are not loaded they are not expected to throw an exception.

Thank you for helping us get to this issue.

Best wishes,
Miroslav
the Telerik team

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answered on 16 Jul 2009, 01:53 AM

hi Miroslav
I'm using Silverlight 2 and Telerik control build version is 2009.1.526.1020. This error only occurs when the node is not expanded. Here is the stack trace of the error I got in my browser:

Error: Sys.InvalidOperationException: ManagedRuntimeError error #4004 in control 'Xaml1': System.IndexOutOfRangeException: Index was outside the bounds of the array.
   at Telerik.Windows.Controls.RadTreeView.RadTreeView_ItemPrepared(Object sender, RadTreeViewItemPreparedEventArgs e)
   at System.EventHandler`1.Invoke(Object sender, TEventArgs e)
   at Telerik.Windows.Controls.RadTreeView.OnItemPrepared(RadTreeViewItemPreparedEventArgs e)
   at Telerik.Windows.Controls.RadTreeView.PrepareTreeViewItemForItem(DependencyObject element, Object item, ItemsControl owner)
   at Telerik.Windows.Controls.RadTreeViewItem.PrepareContainerForItemOverride(DependencyObject element, Object item)
   at System.Windows.Controls.ItemsControl.UpdateContainerForItem(Int32 index)
   at System.Windows.Controls.ItemsControl.RecreateVisualChildren()
   at System.Windows.Controls.ItemsControl.RecreateVisualChildren(IntPtr unmanagedObj)
Source File: http://localhost/myapp/ScriptResource.axd?d=SLdRgtkPsj-3ZQlv_RyuS6aL18JTvjqatIbzRBh72zwTz-vN-Jj8nJTrzI9ghi9-VOZ9j_5U7tFcPksYUTx1pw2&t=ffffffffafbd6209
Line: 461

update: I tried the latest build:2009_2_701 same problem

answered on 20 Jul 2009, 03:11 PM

Hello James,

We were unable to reproduce this issue.
Can you please send us a sample project in order to fix it.
We need some more information about the data source you use and the way you populate RadTreeView items.
May be you try to bind RadTreeView item with out of range data.

However ExpandItemByPath works asynchronously, while GetItemByPath forces layout updates and tries to complete synchronously. Still, even if some of the items are not loaded they are not expected to throw an exception.

Greetings,
Boryana
the Telerik team

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Check out the tips for optimizing your support resource searches.

answered on 28 Jul 2009, 02:46 PM

I have followed the insturctions listed in this thread and everything is working for small expantion paths (below 57). However I am dealing with a dataset that has paths above 100 nodes. Everytime I call ExpandItemByPath with a path above 57 node I get the following exception in the UnhandledException event handler method:

Exception of type 'System.InvalidOperationException' was thrown.

at Telerik.Windows.RadRoutedEventHelper.BuildRoute(DependencyObject element, EventRoute route, RadRoutedEventArgs args)

at Telerik.Windows.RadRoutedEventHelper.RaiseEvent(DependencyObject element, RadRoutedEventArgs args)

at Telerik.Windows.DependencyObjectExtensions.RaiseEvent(DependencyObject element, RadRoutedEventArgs e)

at Telerik.Windows.Controls.RadTreeViewItem.OnPreviewSelected(RadRoutedEventArgs e)

at Telerik.Windows.Controls.RadTreeViewItem.IsSelectedPropertyConstrainValue(DependencyObject d, Object newValue)

at Telerik.Windows.PropertyMetadata.CoerceValue(DependencyObject d, DependencyPropertyChangedEventArgs e, CoerceValueCallback callback)

at Telerik.Windows.PropertyMetadata.<>c__DisplayClass1.<Create>b__0(DependencyObject d, DependencyPropertyChangedEventArgs e)

at System.Windows.DependencyObject.RaisePropertyChangeNotifications(DependencyProperty dp, Object newValue, Object oldValue)

at System.Windows.DependencyObject.SetValueInternal(DependencyProperty dp, Object value, Boolean allowReadOnlySet, Boolean isSetByStyle, Boolean isSetByBuiltInStyle, PropertyInvalidationReason reason)

at System.Windows.DependencyObject.SetValueInternal(DependencyProperty dp, Object value)

at System.Windows.DependencyObject.SetValue(DependencyProperty dp, Object value)

at Telerik.Windows.Controls.RadTreeViewItem.set_IsSelected(Boolean value)

at Telerik.Windows.Controls.RadTreeView.SelectionChanger_SelectionChanged(Object sender, SelectionChangedEventArgs e)

at Telerik.Windows.Controls.SelectionChanger`1.InvokeSelectionChangedEvent()

at Telerik.Windows.Controls.SelectionChanger`1.End()

at Telerik.Windows.Controls.RadTreeView.SetSelectedItem(RadTreeViewItem itemContainer)

at Telerik.Windows.Controls.RadTreeView.HandleItemSelectionFromUI(RadTreeViewItem itemToSelect)

at Telerik.Windows.Controls.RadTreeView.HandleDownArrowKey(KeyEventArgs e)

at Telerik.Windows.Controls.RadTreeView.HandleKeyDown(KeyEventArgs e)

at Telerik.Windows.Controls.RadTreeViewItem.OnKeyDown(KeyEventArgs e)

at System.Windows.Controls.Control.OnKeyDown(Control ctrl, EventArgs e)

at MS.Internal.JoltHelper.FireEvent(IntPtr unmanagedObj, IntPtr unmanagedObjArgs, Int32 argsTypeIndex, String eventName)

Any help on this issue would be apprieciated.

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Programmatic access to treeview items

25 Answers, 1 is accepted