Trouble binding updated properties to view

Question

Hi Guys, 
I have the following code which i want to to populate a combobox based upon the selected item of a treeview.
as depending on what node is chosen will populate the combobox with a different list of report levels.
the combobox is within a user control and i am trying to bind to a dependency property ReportLevel i have in my MainViewModel. if i set the value of the combobox its fine but i want to be able to update it whenever a user choses a different node on the tree.
this is my xaml
<UserControl x:Class="RTHM.ComboboxControl1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup- compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
mc:Ignorable="d"
xmlns:local ="clr-namespace:RTHM.ViewModels"
d:DesignHeight="300" d:DesignWidth="300">
<Grid>
ItemsSource="{Binding Path=Levels}"
IsSynchronizedWithCurrentItem="True"
DisplayMemberPath="Name"
SelectedItem="{Binding Path=SelectedLevel, Mode=TwoWay}"
IsEnabled="{Binding IsEnabled}"/>
my code behind:
public partial class ComboboxControl1 : UserControl
public ComboboxControl1()
InitializeComponent();
DataContext = new MainViewModel();and in my viewmodelprivate ObservableCollection<ReportLevel> _levels;
public ObservableCollection<ReportLevel> Levels
get
return _levels;
set
_levels = value;
NotifyPropertyChanged("Levels");
}my MainViewModel inherits from a base class which has INotifyProperty changed and an implementationpublic class ViewModelBase : INotifyPropertyChanged
public event PropertyChangedEventHandler PropertyChanged;
protected void NotifyPropertyChanged(string propertyName)
if (PropertyChanged != null)
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}any Ideas on how to update the Comboboxs ItemSource dynamically?Thanks in advance

Answer 1

They are presumably in the same datacontext?
Hmmmm
I wonder if you should really have that combo in a separate usercontrol.
Anyhow.
You've Bound the treeview to a collection of whatever that is bound to.
( You haven't explained a bunch of relevant stuff here mate )
Call that a collection of trees.
A tree presumably has a collection of reportlevels in it.
Vaguely like
public class tree()
public observablecollection<reportlevel> reportlevels [get;set;}
But maybe with some propertychange stuff.
Bind selecteditem of the treeview to selectedtree in your viewmodel.
Bind itemssource of the combo to selectedtree.reportlevels.
Hope that helps.
Recent Technet articles: Property List Editing;
Dynamic XAML