main page doesn't get updated after initialisation is finished - xamarin.forms

Question

I am having issues with binding context, after initialisation it doesn't update. so the button is not clickable and the name label doesn't update as its stated in ctor. This is the first and only page.
Page
<Label x:Name="NamesLabels" Text="{Binding Name}"/>
<Button HorizontalOptions="FillAndExpand" Text="Show scanner" Command="{Binding ShowScannerCommand}"/>
public MainPage()
{
InitializeComponent();
}
protected override void OnAppearing()
{
base.OnAppearing();
BindingContext = new MainPageViewModel();
}
//also tried
protected override void OnAppearing()
{
base.OnAppearing();
var context = new MainPageViewModel();
BindingContext = context;
name.Source = context.Name;
btn.Command = context.ShowScannerCommand;
}
ViewModel
public string Name
{
get => _name;
private set
{
_name = value;
NotifyPropertyChanged("Name");
}
}
public ICommand ShowScannerCommand { get; private set; }
public MainPageViewModel()
{
Name = "rwatag";
//have tried _name = "rwatag";
ShowScannerCommand = new Command(() => ShowScanner());
}
void ShowScanner()
{
System.Diagnostics.Debug.WriteLine("result");
}
this is what I get after clicking on button and when debugging the code doesn't get fired
[InputEventReceiver] Slow Input: took 118ms in dispatching, now at finishInputEvent (MotionEvent: event_seq=0, seq=78288, action=ACTION_DOWN)
Resolved pending breakpoint at '/Users/de/Projects/Demo/Demo/View/MainPage.xaml.cs:26,1' to void Demo.MainPage.OnAppearing () [0x00014].
[zygote] Do partial code cache collection, code=61KB, data=59KB
[zygote] After code cache collection, code=61KB, data=59KB
[zygote] Increasing code cache capacity to 256KB

Answer 1

I use your code and it works well on my side. I just add a string _name { get; set; } property and implement the INotifyPropertyChanged interface in MainPageViewModel.
Here is the code example:
public partial class MainPage : ContentPage
{
public MainPage()
{
InitializeComponent();
BindingContext = new MainPageViewModel();
}
}
public class MainPageViewModel : INotifyPropertyChanged
{
string _name { get; set; }
public string Name
{
get => _name;
private set
{
_name = value;
OnPropertyChanged("Name");
}
}
public ICommand ShowScannerCommand { get; private set; }
public MainPageViewModel()
{
Name = "rwatag";
ShowScannerCommand = new Command(() => ShowScanner());
}
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged(string propertyName)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
void ShowScanner()
{
System.Diagnostics.Debug.WriteLine("result");
}
}