Bound textbox value not updated

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WPF

MVVM

Hi everyone,

I've been looking up tutorials for the past few weeks (and even more intensely during the past 3 days) about WPF with mvvm approach and have been missing something which I am not sure of. Cutting to the chase, I have created a test application with 4 classes including the MainWindow (during this tutorial I have purpossedly violated the MVVM principle by merging the model and view model classes just so I can browse my code quicker without having too many tabs in visual studio)

so here's my model and view model class which inherits from ObservableObject class

string _partnumber
int _price
Part _currpart

public string PartNumber
{
     get {return _partnumber;}
     set
      {
          if (value != _partnumber)
          {
              _partnumber = value;
              OnPropertyChanged("PartNumber");
          }
      }
}

//I also have 2 other properties which is written the same way so I'll just keep it short

public int Price
{
   //the usual get, written the same way as PartNumber property
     set
       {
          //just like PartNmber, checks for value and then set it
          OnPropertyChanged("Price");
       }
}

public Part CurrentPart
{
     //the usual get, written the same way as PartNumber property
     set
       {
          //just like PartNmber, checks for value and then set it
          OnPropertyChanged("Part");
       }
}

private ICommand _getpricecommand;

public ICommand GetPriceCommand
 {
            get
            {
                if (_getpricecommand == null)
                {
                    _getpricecommand = new RelayCommand(param => GetPrice(),param => true);
                }
                return _getpricecommand;
            }
}

private void GetPrice()
{
            Part p = new Part();
            p.PartNumber = "6H-4130-01";
            p.price = 7;
            CurrentPart = p;
}

ObservableObject class

public event PropertyChangedEventHandler PropertyChanged;
        
        protected virtual void OnPropertyChanged(string PropertyName)
        {
            PropertyChangedEventHandler hndl = this.PropertyChanged;
            if (hndl != null)
            {
                var e = new PropertyChangedEventArgs(PropertyName);
                hndl(this, e);
            }
        }

        public virtual void RaisePropertyChanged(string PropertyName)
        {
            OnPropertyChanged(PropertyName);
        }

and finally, RelayCommand class

readonly Action<object> _execute;
readonly Predicate<object> _canexecute;

public RelayCommand(Action<object> Execute ) : this(Execute,null)
{

}

public RelayCommand(Action<object> Execute, Predicate<object> CanExecute)
{
    if(Execute == null)
    {
        throw new ArgumentNullException("execute");
    }
    _execute = Execute;
    _canexecute = CanExecute;

}

public event EventHandler CanExecuteChanged
{
    add { CommandManager.RequerySuggested += value; }
    remove { CommandManager.RequerySuggested -= value; }
}

[DebuggerStepThrough]
public bool CanExecute(object parameter)
{
    return _canexecute == null ? true : _canexecute(parameter);
}

public void Execute(object parameter)
{
    _execute(parameter);
}

for the view, which is the MainWindow, I override the OnStartUp with:

MainWindow app = new MainWindow();
Part p = new Part();
app.DataContext = p;
app.Show();

and finally

<Window.Resources>
    <DataTemplate DataType="local:Part" />
</Window.Resources>

<StackPanel DataContext="{Binding CurrentPart}">
            <TextBlock Text="{Binding PartNumber}" Height="50" Width="150" />
            <TextBlock Text="{Binding Price}" Height="50" Width="150" />
            <Button Command="{Binding GetPriceCommand}" Height="50" Width="150" Content="Get Part" />
        </StackPanel>

So at the press of Get Part button, it should display the partnumber in the top textbox and price in bottom textbox, but nothing showed up. I placed breakpoints in GetPrice() and GetPriceCommand but they seem to pass on the properties as they should. What did I miss?