GetBindingExpression returns null in the Loaded event

Question

I'm trying to call the GetBindingExpression method in the Loaded event, but it always returns null.

Is this expected behavior, or am I doing something wrong? If it is expected, after what event do binding expressions become available?

I just create custom control

public partial class LookUp : ComboBox

public static readonly DependencyProperty LookUpItemsSourceProperty =
                           DependencyProperty.Register("LookUpItemsSource"
                           , typeof(IEnumerable)
                           , typeof(LookUp)
                           , new PropertyMetadata(OnItemsSourcePropertyChanged));


public IEnumerable LookUpItemsSource
        {
            get
            {
                return this.GetValue(LookUpItemsSourceProperty) as IEnumerable;
            }
            set
            {
                this.SetValue(LookUpItemsSourceProperty, value);
            }
        }

And use this control in xaml

<Controls:LookUp Name="cb1"  LookUpItemsSource="{x:Static Helper:DataManager.CycleLookUpData}"

Now i want to get binding expression when control initialized that method return null:

cb1.GetBindingExpression(LookUp.LookUpItemsSourceProperty)

Answer 1

x:static will set the value of key, it is not binding expression. You will have to use,

{Binding CycleLookUpData, source={x:static Helper:DataManager}}