WPF HierarchicalDataTemplate TreeView is not Clickable

Question

I have a TreeView with a HierarchicalDataTemplate. The items are filled correctly but I can't click on the TreeView items. (I can't select one, so that is marked blue). I can click in front of the TreeViewItem and then the selected is marked blue. It looks like there is a small box that I can clicked but the not the rest.

Here is my code:

XAML:

<TreeView ItemsSource="{Binding Main.TreeItems}">
    <TreeView.ItemTemplate>
        <HierarchicalDataTemplate ItemsSource="{Binding Path=Children}">
            <TreeViewItem Header="{Binding Path=Header}"/>
        </HierarchicalDataTemplate>
    </TreeView.ItemTemplate>
</TreeView>

Model

public class ITreeItem
{
    public string Header { get; set; }
    public List<ITreeItem> Children { get; set; } 
}

class MainModel : INotifyPropertyChanged
{
    private List<ITreeItem> _treeitems;

    public MainModel()
    {
        _treeitems = new List<ITreeItem>();

        List<ITreeItem> treeList = new List<ITreeItem>();

        ITreeItem myItem1 = new ITreeItem();
        myItem1.Header = "Test1";
        myItem1.Children = new List<ITreeItem>();
        treeList.Add(myItem1);

        myItem1.Header = "Test2";
        myItem1.Children = new List<ITreeItem>();
        treeList.Add(myItem1);

        TreeItems = treeList;          
    }

    public List<ITreeItem> TreeItems
    {
        get
        {
            return _treeitems;
        }
        set
        {
            _treeitems = value;
            OnPropertyChanged("TreeItems");
        }
    }

    public event PropertyChangedEventHandler PropertyChanged;

    private void OnPropertyChanged(string propertyName)
    {
        PropertyChangedEventHandler handler = PropertyChanged;

        if (handler != null)
        {
            handler(this, new PropertyChangedEventArgs(propertyName));
        }
    }
}

Kabob

Amazing, some examples use the TreeViewItem in this way from what I have seen. I've been stuck for ages with the same issue. – Pinna

Answer 1

In your XAML, instead of using a <TreeViewItem> under the HierarchicalDataTemplate, try using another control, such as a TextBlock:

<TextBlock Text="{Binding Path=Header}"/>

Subroutine

thanks. that works well. is there a waya to expand the items automatically in xaml? – Kabob

@Kabob The way I would do it is create an bool IsExpanded Property in your ITreeItem class, have the initial value set to True, and have that class implement INotifyPropertyChanged as well. Then in your Resources have a Style that targets the TreeViewItem. – Subroutine

@Kabob Here is the style: <Style TargetType="TreeViewItem"> <Setter Property="IsExpanded" Value="{Binding IsExpanded, Mode=TwoWay}" /> </Style> – Subroutine

Answer 2

The previous solution avoids the problem. There is a way to use header to select a TreeViewItem: on the MSDN website we can find an example which uses header and where TreeViewItem are clickable. Does someone have an idea why here it's not possible?

I personally hacked that using MouseButtonEventHandler adding a foreach on items with isSelected = false; and then ((TreeViewItem)sender).IsSelected = true; but that's dirty.

Hexagon

It's because the OP is using an ItemTemplate. When you use an ItemTemplate, a <TreeViewItem> is implicitly created. This explains why TreeViewItems are still generated even though a TextBlock is used. It is common practice to use a TextBlock to render TreeViewItems which use templates. – Subroutine