Changing Property in code behind does not update view - xamarin.forms

Question

When I change my property which is a model object, The view does not update unless I reassign the binding context. I am not using mvvm, so no view model.
public partial class MainPage : ContentPage
{
private MySource _myCurrentSource = new MySource("yolor");
public MySource MyCurrentSource {
get { return _myCurrentSource; }
set {_myCurrentSource = value; }
}
public MainPage()
{
InitializeComponent();
MyCurrentSource = _myCurrentSource;
MainStack.BindingContext = MyCurrentSource;
label.SetBinding(Label.TextProperty, new Binding("SourceString"));
}
private void Button_Clicked(object sender, EventArgs e)
{
MyCurrentSource = new MySource("new string");
//property changed
MainStack.BindingContext = MyCurrentSource;
}
}
I want to get rid of : MainStack.BindingContext = MyCurrentSource;
This is what my xaml looks like
<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
x:Class="DataBindingPlayGround.MainPage">
<StackLayout Padding="10, 0" x:Name="MainStack" HorizontalOptions="Center"
VerticalOptions="CenterAndExpand">
<Label x:Name="label" Text="TEXT" FontSize="48" />
<Button Text="Change" Clicked="Button_Clicked"/>
</StackLayout>
</ContentPage>
Model class:
public class MySource
{
public MySource(string str)
{
SourceString = str;
}
public string SourceString { get; set; }
}

Answer 1

Modify MySource class as follows to have a try:
public class MySource : INotifyPropertyChanged
{
public MySource(string str)
{
sourceString = str;
}
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged(string propertyName)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
private string sourceString;
public double SourceString
{
set
{
if (sourceString != value)
{
sourceString = value;
OnPropertyChanged("SourceString");
}
}
get
{
return sourceString;
}
}
}
=============================Update=================================
Although not understanding the logic of your application, if you want to make MyCurrentSource works. You will also need to use INotifyPropertyChanged:
public partial class MainPage : ContentPage ,INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged(string propertyName)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
private MySource _myCurrentSource;
public MySource MyCurrentSource
{
set
{
if (_myCurrentSource != value)
{
_myCurrentSource = value;
OnPropertyChanged("MyCurrentSource");
}
}
get
{
return _myCurrentSource;
}
}
public MainPage()
{
InitializeComponent();
_myCurrentSource = new MySource("yolor");
//MyCurrentSource = _myCurrentSource;
MainStack.BindingContext = _myCurrentSource ;
label.SetBinding(Label.TextProperty, new Binding("SourceString"));
}
private void Button_Clicked(object sender, EventArgs e)
{
_myCurrentSource = new MySource("new string");
//property changed
MainStack.BindingContext = _myCurrentSource;
}
}
Or you can directly set new Model when BindingContext.
public partial class MainPage : ContentPage
{
public MainPage()
{
InitializeComponent();
MainStack.BindingContext = new MySource("yolor");
label.SetBinding(Label.TextProperty, new Binding("SourceString"));
}
private void Button_Clicked(object sender, EventArgs e)
{
//property changed
MainStack.BindingContext = new MySource("new string");
}
}

Answer 2

This is finally what worked for me, in case anyone has similar situation:
Source classes below:
public class FirstSource
{
public string sourceString;
public string SourceString { get; set; }
public int SourceOneProp2 { get; set; }
public FirstSource(string str, int num)
{
SourceString = str;
SourceOneProp2 = num;
}
}
public class SecondSource
{
public string ExampleField { get; set; }
public int SourceTwoProp2 { get; set; }
public SecondSource(string exampleField, int num)
{
ExampleField = exampleField;
SourceTwoProp2 = num;
}
}
ViewModel (Decided to use to make task easier)
class MainPageViewModel : BaseViewModel
{
private FirstSource _sourceOne;
private SecondSource _sourceTwo;
public FirstSource SourceOne
{
get { return _sourceOne; }
set { SetValue(ref _sourceOne, value); }
}
public SecondSource SourceTwo
{
get { return _sourceTwo; }
set { SetValue(ref _sourceTwo, value); }
}
}
Code Behind:
public partial class MainPage : ContentPage
{
int counter = 0;
private MainPageViewModel ViewModel
{
get { return BindingContext as MainPageViewModel; }
set { BindingContext = value; }
}
public MainPage()
{
InitializeComponent();
ViewModel = new MainPageViewModel();
ViewModel.SourceOne = new FirstSource("init1", 10);
ViewModel.SourceTwo = new SecondSource("init2", 20);
}
private void Button_Clicked(object sender, EventArgs e)
{
counter += 1;
ViewModel.SourceOne = new FirstSource("Changed1", 100+counter);
}
private void Button_Clicked_1(object sender, EventArgs e)
{
counter += 1;
ViewModel.SourceTwo = new SecondSource("Changed2", 200+counter);
}
}
XAML/UI
<StackLayout Padding="10, 0" x:Name="MainStack" HorizontalOptions="Center" VerticalOptions="Start">
<Label x:Name="label" Text="{Binding Path=SourceOne.SourceString}" FontSize="48" />
<Label Text="{Binding Path=SourceOne.SourceOneProp2}" />
<Button Text="Change" Clicked="Button_Clicked"/>
<StackLayout Padding="10, 0" x:Name="SecondStack">
<Label x:Name="secondLabel" Text="{Binding Path=SourceTwo.ExampleField}" FontSize="48" />
<Label Text="{Binding Path=SourceTwo.SourceTwoProp2}" />
<Button Text="Change" Clicked="Button_Clicked_1"/>
</StackLayout>
</StackLayout>