wpf treeview mvvm

Question

hi I am trying to populate a treeview using mvvm but the tree does not display any data. I have a Employee list which is a property in my vm which contains he employee data. the xaml is as follows.

                <Style TargetType="{x:Type TreeViewItem}">
                    <Setter Property="FontWeight" Value="Normal" />

                </Style>
            </TreeView.ItemContainerStyle>

            <TreeView.ItemTemplate>

                <HierarchicalDataTemplate ItemsSource="{Binding EmpList}" >
                    <TextBlock Text="{Binding EmpName}"/>

                </HierarchicalDataTemplate>

            </TreeView.ItemTemplate>

        </TreeView>

Is there anything i am missing here.

thanks

Answer 1

Check out Josh Smith's article on exactly this topic... Helped me no end!

p.s. Looks like you're missing the DataType property on the HierarchicalDataTemplate, e.g.

<HierarchicalDataTemplate
    DataType="{x:Type local:ItemType}"
    ItemsSource="{Binding ...}" >

Answer 2

Hi Ian's suggested article indeed is a great read!

The trick is that you should specify how the Treeview shows its items through type specific (Hierarchical)DataTemplates. You specify these datatemplates in the Treeview's resources (or higher up the visual tree if you want to reuse them in more treeviews).

I tried to simulate what you want:

<Window x:Class="TreeViewSelection.Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="clr-namespace:TreeViewSelection"
    Title="Window1" Height="300" Width="300">
    <StackPanel>
        <TreeView ItemsSource="{Binding Enterprises}">
            <TreeView.Resources>
                <!-- template for showing the Enterprise's properties
                     the ItemsSource specifies what the next nested level's
                     datasource is -->
                <HierarchicalDataTemplate DataType="{x:Type local:Enterprise}"
                                          ItemsSource="{Binding EmpList}">
                    <Label Content="{Binding EntName}"/>
                </HierarchicalDataTemplate>
                <!-- the template for showing the Employee's properties-->
                <DataTemplate DataType="{x:Type local:Employee}">
                    <Label Content="{Binding EmpName}"/>
                </DataTemplate>
            </TreeView.Resources>
        </TreeView>
    </StackPanel>
</Window>


    using System.Collections.ObjectModel;
using System.Windows;

namespace TreeViewSelection
{
    public partial class Window1 : Window
    {
        public ObservableCollection<Enterprise> Enterprises { get; set; }
        public Window1()
        {
            InitializeComponent();
            Enterprises = new ObservableCollection<Enterprise>
                            {
                                new Enterprise("Sweets4Free"),
                                new Enterprise("Tires4Ever")
                            };
            DataContext = this;
        }
    }

    public class Enterprise : DependencyObject
    {
        public string EntName { get; set; }
        public ObservableCollection<Employee> EmpList { get; set; }

        public Enterprise(string name)
        {
            EntName = name;
            EmpList = new ObservableCollection<Employee>
                        {
                            new Employee("John Doe"),
                            new Employee("Sylvia Smith")
                        };
        }
    }
        public class Employee : DependencyObject
        {
            public string EmpName { get; set; }
            public Employee(string name)
            {
                EmpName = name;
            }
        }
    }