Tree View IsSelected with hierarchical data template

Question

I have found a couple examples of binding an IsSelected Property in the view model. However none of these deal with a TreeView with Hierachical data templates.

My Hierachy is like this

VM_Part
- VM_Step
- VM_Step
- VM_Step
VM_Part
- VM_Step
- VM_Step

I would like to be able to select multiple VM_Part instances or Multiple VM_Steps under one part. The idea being I can have a context menu and perform various commands on the selected items

<Window x:Class="NameSpace1.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    xmlns:local="clr-namespace:Hipot_Sequence_Editor"
    xmlns:xctk="http://schemas.xceed.com/wpf/xaml/toolkit"

    mc:Ignorable="d"
    Title="MainWindow" Height="677.538" Width="896.456">

<Window.DataContext>
    <local:VM_Main></local:VM_Main>
</Window.DataContext>
<Grid>
    <TreeView x:Name="treeView" Grid.Column="1" HorizontalAlignment="Left" Height="628" Margin="10.2,10,0,0" VerticalAlignment="Top" Width="237" Grid.RowSpan="2" ItemsSource="{Binding Parts}">
        <TreeView.Resources>
            <HierarchicalDataTemplate DataType="{x:Type viewModels:VM_Part}" ItemsSource="{Binding VM_Steps}">
                <StackPanel Orientation="Horizontal">
                    <TextBlock Text="{Binding SequenceNumber}" />
                    <TextBlock Text=" - "></TextBlock>
                    <TextBlock Text="{Binding PartNumber}" />
                </StackPanel>
            </HierarchicalDataTemplate>
            <DataTemplate DataType="{x:Type viewModels:VM_Step}">
                <StackPanel Orientation="Horizontal">
                    <TextBlock Text="{Binding Name}" />
                </StackPanel>
            </DataTemplate>
        </TreeView.Resources>
    </TreeView>
</Grid>

This seems to me the closet example to what I need. I tried the first answered suggested

<TreeView.Resources>
    <Style TargetType="TreeViewItem">
        <Setter Property="IsSelected"
                Value="{Binding Path=IsSelected, Mode=TwoWay}" />
    </Style>
</TreeView.Resources>

However it seems that this code assumes IsSelected is in VM_Main and not in VM_Part or VM_Step

I just tried the solution you posted and it worked for me. There must be something else going on if the data context for your items is not what you expect. How did you confirm that the data context for the items in `VM_Main`? Also, what does the `Parts` property look like in `VM_Main`? Your xaml also appears to be referencing a namespace called `viewModels` which does not appear in the code you shared. — Xavier, Apr 03 '18 at 04:35

score 1 · Accepted Answer · answered Apr 03 '18 at 07:21

each TreeViewItem in a hierarchy

VM_Part TreeViewItem
- VM_Step TreeViewItem
- VM_Step TreeViewItem
- VM_Step TreeViewItem

has its own DataContext (VM_Part or VM_Step)

so if VM_Part and VM_Step have IsSelected property, then style for TreeViewItem is defined correctly

<Style TargetType="TreeViewItem">
    <Setter Property="IsSelected"
            Value="{Binding Path=IsSelected, Mode=TwoWay}" />
</Style>

however, multiselection in TreeView is probably simpler with CheckBoxes added to item template and bound to view model IsSelected property:

<HierarchicalDataTemplate DataType="{x:Type viewModels:VM_Part}" ItemsSource="{Binding VM_Steps}">
    <StackPanel Orientation="Horizontal">
        <CheckBox IsChecked="{Binding IsSelected, UpdateSourceTrigger=PropertyChanged}" />
        <TextBlock Text="{Binding SequenceNumber}" />
        <TextBlock Text=" - "/>
        <TextBlock Text="{Binding PartNumber}" />
    </StackPanel>
</HierarchicalDataTemplate>
<DataTemplate DataType="{x:Type viewModels:VM_Step}">
    <StackPanel Orientation="Horizontal">
        <CheckBox IsChecked="{Binding IsSelected, UpdateSourceTrigger=PropertyChanged}" />
        <TextBlock Text="{Binding Name}" />
    </StackPanel>
</DataTemplate>

Tree View IsSelected with hierarchical data template

1 Answers1