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MVVM - select item in TreeView and show its properties on a ListView using binding

I'm new to MVVM. I created a TreeView with hierarchy of 3 levels: level1: Program, level2: Action, level3: Position. I also created a ListView under the TreeView (see xaml) . Right now the items of the ListView are not bound to anything (the names "Type", "Speed" are only placeholders.)
When selecting an item from level2 (Action) in the TreeView, i'd like to see it's properties (type, speed) appear on the ListView below.
Is there a way to do it through a change in the View only (xaml), without using code in the ViewModel ? maybe there's a way to use a certain binding, that can be changed when pressing on the item in the TreeView?
xaml (model):
<TreeView
Grid.Row="0"
x:Name="MainTreeView"
HorizontalAlignment="Stretch"
Margin="10"
VerticalAlignment="Stretch"
ItemsSource="{Binding Programs}">
<TreeView.ItemTemplate>
<HierarchicalDataTemplate ItemsSource="{Binding Actions}" DataType="{x:Type VM:ProgramVM}">
<Label Content="{Binding ProgramName}"/>
<HierarchicalDataTemplate.ItemTemplate>
<HierarchicalDataTemplate ItemsSource="{Binding Poses}" DataType="{x:Type VM:ActionVM}">
<Label Content="{Binding Actiontype}"/>
<HierarchicalDataTemplate.ItemTemplate>
<DataTemplate DataType="{x:Type VM:PositionVM}">
<Label Content="{Binding PosName}"/>
</DataTemplate>
</HierarchicalDataTemplate.ItemTemplate>
</HierarchicalDataTemplate>
</HierarchicalDataTemplate.ItemTemplate>
</HierarchicalDataTemplate>
</TreeView.ItemTemplate>
</TreeView>
<ListView Grid.Row="1" Margin="10" Name="lvUsers">
<ListView.View>
<GridView>
<GridViewColumn Header="Type" Width="100" DisplayMemberBinding="{Binding Type}" />
<GridViewColumn Header="Speed" Width="100" DisplayMemberBinding="{Binding Speed}" />
</GridView>
</ListView.View>
</ListView>

This is a well known issue with the treeview in WPF. You have to create an 'is selected' property for each object in your tree so that you know what the user has chosen, then you can just show the selected object in your listview.
It's been a while since I played with a treeview, but here are some of the links that I think helped me in the past.
Data binding to SelectedItem in a WPF Treeview
WPF MVVM TreeView SelectedItem

Combobox not showing groupings

I'm trying to organize the items in a combobox into groups. To do this I've created an object that has project and group name strings. I then set the GroupStyle and ItemTemplate to display these values. However, Currently, only the project string is displayed in the combobox (and the box has a red border, indicating some kind of error).
Here's the xaml for my combobox:
<ComboBox x:Name="comboBoxProjects" Margin="165,90,28,0" Grid.Column="0" VerticalAlignment="Top" Height="25"
IsSynchronizedWithCurrentItem="True" SelectedIndex="0" Style="{StaticResource ComboBoxDefault}"
ItemsSource="{Binding Path=ProjectClientSelections.ProjectGroupItems,Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
SelectedItem="{Binding Path=ProjectClientSelections.SelectedProject, UpdateSourceTrigger=PropertyChanged}">
<ComboBox.GroupStyle>
<GroupStyle>
<GroupStyle.HeaderTemplate>
<DataTemplate>
<TextBlock Text="{Binding GroupName}"/>
</DataTemplate>
</GroupStyle.HeaderTemplate>
</GroupStyle>
</ComboBox.GroupStyle>
<ComboBox.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding Project}"/>
</DataTemplate>
</ComboBox.ItemTemplate>
</ComboBox>
Does anyone see where I'm going wrong?

In GroupStyle, the DataContext is not your item (the type contained in your ItemsSource), but a CollectionViewGroup object, which is formed based on the collection of items that you have grouped. Because of this you have to declare a binding path to one of the properties in CollectionViewGroup, for example, based on your code you probably want to use Name property. See MSDN CollectionViewGroup Class
Change your GroupStyle.HeaderTemplate to this:
<DataTemplate>
<TextBlock Text="{Binding Name}" />
</DataTemplate>
You don't show how you have formed your GroupDescriptions. If you have not grouped the items already, you can do it in following way (assuming the XAML you have provided is contained inside Window and Window's and GroupBox's DataContext is the same):
<Window.Resources>
<CollectionViewSource
Source="{Binding ProjectClientSelections.ProjectGroupItems}"
x:Key="GroupedProjectItems">
<CollectionViewSource.GroupDescriptions>
<PropertyGroupDescription
PropertyName="GroupName" />
</CollectionViewSource.GroupDescriptions>
</CollectionViewSource>
</Window.Resources>
After this change GroupBox ItemSource binding to the following (directly to CollectionViewSource resource):
ItemsSource="{Binding Source={StaticResource GroupedProjectItems}}"

WPF ListView->GridView->StackPanel

I have a ListView that uses GridView to display some data. One of the fields contains a list with image paths. Therefore I defin a GridViewColumn and create a DataTemplate. Dis DataTemplate contains another ListView with the Images list as new DataContext. When I don't write anything in the inner StackPanel, I can see that a list of string (in the format AppName.ClassName) is displayed in left to right order.
But whenever I try to display the strings as something else, eg
<Image Source="{Binding Name}" Height="32"/>
I get an System.Windows.Markup.XamlParseException . Even with data binding I get an exception. Eg
<Image Source="Images/Camera_32xLG.png" Height="32"/>
. Any hint, what I might do wrong?
<GridViewColumn Header="Images">
<GridViewColumn.CellTemplate>
<DataTemplate>
<ListView ItemsSource="{Binding Images}" BorderThickness="0">
<ListView.ItemsPanel>
<ItemsPanelTemplate>
<StackPanel Orientation="Horizontal">
--> here is where I don't know what to do next
</StackPanel>
</ItemsPanelTemplate>
</ListView.ItemsPanel>
</ListView>
</DataTemplate>
</GridViewColumn.CellTemplate>
</GridViewColumn>

Since the StackPanel is a part of ItemsPanelTemplate, you should just define it's properties and not explicitly add any children. The way to specify appearance of each item is through the ListView.ItemTemplate property:
<ListView ItemsSource="{Binding Images}" BorderThickness="0">
<ListView.ItemsPanel>
<ItemsPanelTemplate>
<StackPanel Orientation="Horizontal" />
</ItemsPanelTemplate>
</ListView.ItemsPanel>
<ListView.ItemTemplate>
<DataTemplate>
<Image Source="{Binding Name}" Height="32" />
</DataTemplate>
</ListView.ItemTemplate>
</ListView>

How to access element (Combo Box) in XAML from code behind

How do I access a control in XAML that is nested in a GridViewColumn.CellTemplate? By accessing the combo box I want to set its ItemsSource in the code behind.
Code:
<GridViewColumn Width="80">
<GridViewColumnHeader Content="UseCLUT"/>
<GridViewColumn.CellTemplate>
<DataTemplate>
<Grid>
<TextBlock Text="{Binding Path=UseCLUT}" Style="{StaticResource GridBlockStyle}"/>
<ComboBox x:Name="combTrueFalse" SelectedItem="{Binding Path=UseCLUT}" Style="{StaticResource GridEditStyle}" />
</Grid>
</DataTemplate>
</GridViewColumn.CellTemplate>
</GridViewColumn>
I have named the comboBox as combTrueFalse and tried to referenced it in the code behind but it could not be found.

I find a work around to the problem.
I have set the collection of the combo box to a class which contains the collection for the combox's selection.
The mainWindow class contains the data class's variable.
ItemsSource="{Binding ElementName=mainWindow, Path=data.comboxTFSmall}"
Meaning to say I have set the combox's item towards a Class which contains the collection and not from the code behind.
<GridViewColumn Width="80" >
<GridViewColumnHeader Content="UseCLUT"/>
<GridViewColumn.CellTemplate>
<DataTemplate>
<Grid>
<TextBlock Text="{Binding Path=UseCLUT, Mode=TwoWay}" Style="{StaticResource GridBlockStyle}"/>
<ComboBox ItemsSource="{Binding ElementName=mainWindow, Path=data.comboxTFSmall}" SelectedValue="{Binding Path=UseCLUT}" Style="{StaticResource GridEditStyle}" />
</Grid>
</DataTemplate>
</GridViewColumn.CellTemplate>
</GridViewColumn>
Please do correct me if you find that my explanation is misleading thanks.
regards

Can't show image and textblock inside a GridView

This is my simple code to do this:
<Grid>
<ListView>
<ListView.View>
<GridView>
<GridViewColumn>
<GridViewColumn.CellTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal">
<Image Width="16" Height="16" Source="c:\myimage.jpg" />
<TextBlock Text="Image Name"/>
</StackPanel>
</DataTemplate>
</GridViewColumn.CellTemplate>
</GridViewColumn>
</GridView>
</ListView.View>
</ListView>
</Grid>
But except the empty header, nothing shows up.
This is my first time using GridView. Am I missing something ?

Your ListView has no items, the CellTemplate is applied to each item in the list and if there are no items nothing will be shown. Did you perhaps mean to change the Header instead?

If you are not binding a source then it is not going to generate any rows. Show your XAML or code behind for binding a source.

You probably don't want to use CellTemplate. Here is an intro-level example of ListView: http://www.switchonthecode.com/tutorials/wpf-tutorial-using-the-listview-part-1