Label Text Not Updating From Bindable Property - xaml

Question

I have a very simple form that I'm using to experiment with BindableProperty. Here's the XAML for the form
<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:local="clr-namespace:MyBindableProperty"
x:Class="MyBindableProperty.MainPage">
<StackLayout>
<local:MyLabel x:Name="BindingLabel" Text="{Binding Text}" MyText="{Binding Text}"
VerticalOptions="Center"
HorizontalOptions="Center" />
<Entry x:Name="BindingEntry" Text="{Binding Text, Mode=TwoWay}"/>
<Entry x:Name="BindingEntry2" Text="{Binding Text, Mode=TwoWay}"/>
<Button x:Name="BindingButton" Text="Reset"/>
</StackLayout>
</ContentPage>
And here is the code behind
public partial class MainPage : ContentPage
{
public DataSourceClass DataSourceObject { get; set; }
public MainPage()
{
DataSourceObject = new DataSourceClass { Text = "Test1" };
BindingContext = DataSourceObject;
InitializeComponent();
BindingButton.Clicked += BindingButton_Clicked;
}
private void BindingButton_Clicked(object sender, EventArgs e)
{
var boundText = this.BindingLabel.Text;
var boundMyText = this.BindingLabel.MyText;
DataSourceObject.Text = "Test2";
}
}
Finally, here is the custom label class used in the XAML -
public class MyLabel : Label
{
public string MyText
{
get
{
return (string)GetValue(MyTextProperty);
}
set
{
SetValue(MyTextProperty, value);
}
}
public static readonly BindableProperty MyTextProperty = BindableProperty.Create(nameof(MyText), typeof(string), typeof(MyLabel), "Test", BindingMode.TwoWay, propertyChanged: MyTextChanged);
public static void MyTextChanged(BindableObject bindable, object oldValue, object newValue)
{
((MyLabel)bindable).TextChanged(newValue.ToString());
}
public void TextChanged(string newText)
{
Device.BeginInvokeOnMainThread(() => this.Text = newText);
}
}
The issues I'm having are
when the page initialises the MyTextChanged handler fires, but not after any subsequent changes
when the Reset button is clicked the value in DataSourceObject.Text is correctly updated with the value from the Entry element
no matter how I try to set the values of BindingLabel and BindingEntry2 they never reflect the values of DataSourceObject.Text after the page has loaded.
Any help would be greatly appreciated.

Answer 1

I stumbled across this so I updated the DataSourceClass from this
public class DataSourceClass
{
public string Text { get; set; }
}
to this
public class DataSourceClass : INotifyPropertyChanged
{
private string _text;
public string Text
{
get
{
return _text;
}
set
{
_text = value;
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs("Text"));
}
}
}
public event PropertyChangedEventHandler PropertyChanged;
}
and now everything works.
I thought BindableProperty was meant to supersede INotifyPropertyChanged?