Question

I have list with items in my data class:

 public ObservableCollection<Node> NodesFromDatabase
    {
        get 
        {
            if (_nodesFromDatabase == null)
                _nodesFromDatabase =GenerateMenuNodes();
            return _nodesFromDatabase ;
        }
        set 
        {
            _nodesFromDatabase = value;
        }
    }

And property in control to which i want bind this data:

       public ObservableCollection<Node> Nodes
        {
            get { return (ObservableCollection<Node>)GetValue(NodesProperty); }
            set
            {
                SetValue(NodesProperty, value);
            }
        }

        private static DependencyProperty NodesProperty =
   DependencyProperty.Register(
       "Nodes",
       typeof(ObservableCollection<Node>),
       typeof(Control),new PropertyMetadata(new  ObservableCollection<Node>()));

In xaml i have such code:

    <Grid Background="White">
    <Grid.DataContext>
        <local:DataFromDataBase x:Name="database" />
    </Grid.DataContext>


    <local:Control Nodes="{Binding NodesFromDatabase}" />                
</Grid>

And i have strange logic behind this code.

My NodesFromDatabase property is fired in get statement but control Nodes set statement not firing! What i am doing wrong with it?

Answer 1

Dependency properties that are set in XAML can bypass the CLR wrapper. You should create a property-changed callback in the property metadata if you want to know when the property is changed.