Could not bind to nested BindableProperty - xamarin.forms

Question

I have created bindable property called Text in TargetClass.cs. That Text property is nested bindable property.
TargetClass.cs :
public class TargetClass : BindableObject
{
public static readonly BindableProperty TextProperty =
BindableProperty.Create("Text", typeof(string), typeof(TargetClass), "Default", BindingMode.TwoWay, null,
OnTextChanged);
private static void OnTextChanged(BindableObject bindable, object oldValue, object newValue)
{
}
public string Text
{
get
{
return (string)GetValue(TextProperty);
}
set
{
SetValue(TextProperty, value);
}
}
}
Then I have created MyView.cs
public class MyView : ContentView
{
private TargetClass target;
Label label;
public TargetClass Target
{
get
{
return target;
}
set
{
target = value;
label.Text = target.Text;
}
}
public MyView()
{
label = new Label();
label.FontSize = 50;
Content = label;
}
}
ViewModel.cs :
public class ViewModel : INotifyPropertyChanged
{
private string m_text = "New Value";
public string TextValue
{
get { return m_text; }
set
{
m_text = value;
OnPropertyChanged("TextValue");
}
}
public event PropertyChangedEventHandler PropertyChanged;
public void OnPropertyChanged(string propertyName = null)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
}
MainPage.xaml :
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:d="http://xamarin.com/schemas/2014/forms/design"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d"
xmlns:local="clr-namespace:BindingDemo"
x:Class="BindingDemo.MainPage">
<ContentPage.BindingContext>
<local:ViewModel />
</ContentPage.BindingContext>
<ContentPage.Resources>
<ResourceDictionary>
<local:TargetClass x:Key="target" Text="{Binding TextValue}"/>
</ResourceDictionary>
</ContentPage.Resources>
<StackLayout>
<local:MyView Target="{StaticResource target}"/>
</StackLayout>
It is working when I give some string value to Text property like,
<ContentPage.BindingContext>
<local:ViewModel />
</ContentPage.BindingContext>
<ContentPage.Resources>
<ResourceDictionary>
<local:TargetClass x:Key="target" Text="Hello World"/>
</ResourceDictionary>
</ContentPage.Resources>
<StackLayout>
<local:MyView Target="{StaticResource target}"/>
</StackLayout>
in xaml.
But it doesnt work in MVVM binding When I bind the Text property like,
<ContentPage.BindingContext>
<local:ViewModel />
</ContentPage.BindingContext>
<ContentPage.Resources>
<ResourceDictionary>
<local:TargetClass x:Key="target" Text="{Binding TextValue}"/>
</ResourceDictionary>
</ContentPage.Resources>
<StackLayout>
<local:MyView Target="{StaticResource target}"/>
</StackLayout>
There is no problem with MVVM binding(ViewModel.cs) because it works well with another bindable property.
But it works if the Text property is added in MyView.cs and used like MyView.Text. It doesn't work only when it is added in TargetClass.cs and used like MyView.TargetClass.Text.
Is it possible to use the nested property in data binding in Xamarin Forms?

Answer 1

I don't think objects in the resource dictionary get a BindingContext assigned to them.
So you should modify it from code-behind to assign a context to any resource of type BindableObject
in your page.axml.cs:
protected override void OnBindingContextChanged()
{
base.OnBindingContextChanged();
if (this.Resources != null)
{
foreach (var resource in this.Resources.Values.OfType<BindableObject>())
{
resource.BindingContext = this.BindingContext;
}
}
}