CODEWITHSUNDEEP
c#wpfxamlmvvmtreeview
hoetz
hoetz

Reputation: 2388

WPF treeview does not show child nodes when not adding them in vm's constructor

I have a strange problem with a WPF treeview. In my viewmodel I am doing this:

private ObservableCollection<ITreeItem> _Tree = new ObservableCollection<ITreeItem>();
public ObservableCollection<ITreeItem> Tree
{
    get { return this._Tree; }
}

Now when I add some dummy Parent / child data in the constructor of the viewmodel like this:

var parent = new ParentItem(1, "test", "test2");
this.Tree.Add(parent);
for (int i = 0; i < 10; i++)
{
    parent.Childs.Add(new Child { Name= "test", Description= "test2" });
}
parent.IsExpanded = true;

the tree is displaying correctly.

However, as soon as I am adding some child items via a method (with dispatcher) they do not show at all. When i call this method, for example, only the root node is showing.

public void Update()
{
    DispatcherSingleton.Instance.CurrentDispatcher.BeginInvoke(DispatcherPriority.Normal, 
        new Action(delegate
        {
            var parent = new ParentItem(1, "test", "test2");
            this.Tree.Add(parent);
            for (int i = 0; i < 10; i++)
            {
                parent.Childs.Add(new Child { Name= "test", Description= "test2" });
            }
            parent.IsExpanded = true;
        })
    );
}

Here is the XAML for the treeview

<ResourceDictionary>
    <Style TargetType="TreeViewItem" x:Key="itmContStyle">
        <Setter Property="IsExpanded" Value="{Binding IsExpanded, Mode=TwoWay}" />
    </Style>
    <Style TargetType="{x:Type TreeViewItem}">
        <Setter Property="IsExpanded" Value="{Binding IsExpanded, Mode=TwoWay}" />
        <Setter Property="IsSelected" Value="{Binding IsSelected, Mode=TwoWay}" />
    </Style>
    <HierarchicalDataTemplate x:Key="hDataTemplate"  ItemsSource="{Binding Childs}">
        <StackPanel Orientation="Horizontal">
            <Image Source="{Binding Image, Mode=TwoWay}" Margin="1" />
            <Image x:Name="currentImage" Source="/WpfApp;component/Resources/Images/ac.png" Visibility="Collapsed"></Image>
            <TextBlock Text="{Binding SortOrder}" Margin="1" />
            <TextBlock Text="." Margin="0,1,1,0" />
            <TextBlock Text="{Binding Bezeichnung}" Margin="1" />
        </StackPanel>
        <HierarchicalDataTemplate.Triggers>
            <DataTrigger Binding="{Binding RelativeSource={RelativeSource AncestorType=TreeViewItem}, Path=IsSelected}" Value="True">
                <Setter TargetName="currentImage" Property="Visibility" Value="Visible"/>
            </DataTrigger>
        </HierarchicalDataTemplate.Triggers>
    </HierarchicalDataTemplate>
</ResourceDictionary>

...

<TreeView  HorizontalAlignment="Stretch"  VerticalAlignment="Top" 
           BorderThickness="0" 
           ItemsSource="{Binding Tree}"            
           ItemContainerStyle="{StaticResource itmContStyle}" ItemTemplate="{StaticResource hDataTemplate}">
</TreeView>

Upvotes: 1

Views: 1427

Answers (1)

Sheridan
Sheridan

Reputation: 69959

It appears that you have got your naming mixed up. In your code, you show this line:

parent.Childs.Add(new Child { Name= "test", Description= "test2" });

This makes me think that your data type has a Childs property. But then in your XAML, you have this:

<HierarchicalDataTemplate x:Key="hDataTemplate"  ItemsSource="{Binding ChildSteps}">
    ...
</HierarchicalDataTemplate>

I'm guessing that one of these is wrong. So, try this XAML instead:

<HierarchicalDataTemplate x:Key="hDataTemplate"  ItemsSource="{Binding Childs}">
    ...
</HierarchicalDataTemplate>

Upvotes: 1

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