C# Wpf app: does anyone know how to get the [NotifyPropertyChangedInvocator] statement to work?

Question

this is what the code looks like 

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using System.ComponentModel;

namespace WpfApplication6
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window, INotifyPropertyChanged
    {
        private string text;

        public string Text
        {
            get { return text; }
            set
            {
                text = value;
                OnPropertyChanged("Text");
            }
        }

        public MainWindow()
        {
            Text = "Some Text";
            DataContext = this;
            InitializeComponent();
        }

        private void Button_Click(object sender, RoutedEventArgs e)
        {
            Text = "Another Text";
        }

        public event PropertyChangedEventHandler PropertyChanged;

        [NotifyPropertyChangedInvocator]
        protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
        {
            PropertyChangedEventHandler handler = PropertyChanged;
            if (handler != null) handler(this, new PropertyChangedEventArgs(propertyName));
        }
    }
}

and the [NotifyPropertyChangedInvocator] doesn't work. does anyone know if i have to use more using commands or what?

Answer 1

you don't need that to implement INotifyPropertyChanged.  from what I can find that attributed is used by the resharper tool to refactor any properties decorated with it to support property change notification.

andy

Answer 2

Hi Heerabanani,

Separate the Model from the Mainwindow and Implement INotifyPropertyChanged in the Model.

public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
            DataContext = new ViewModel();
        }

        private void Button_Click(object sender, RoutedEventArgs e)
        {
            (this.DataContext as ViewModel).Text = "Bye WPF";
        }
    }

    public class ViewModel : INotifyPropertyChanged
    {
        private string text;

        public string Text
        {
            get { return text; }
            set
            {
                text = value;
                OnPropertyChanged("Text");
            }
        }

        public ViewModel()
        {
            this.Text = "Hi WPF";
        }

        public event PropertyChangedEventHandler PropertyChanged;

        protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
        {
            PropertyChangedEventHandler handler = this.PropertyChanged;
            if (handler != null) handler(this, new PropertyChangedEventArgs(propertyName));
        }
    }

I checked it. It works fine

---

srithar

Answer 3

The NotifyPropertyChangedInvocator attribute is a Resharper feature: http://www.spikie.be/blog/post/2013/07/02/Making-Resharper-and-MVVM-Lights-ViewModelBase-play-nice.aspx

You could simply remove it from your code in order for it to compile:

         public event PropertyChangedEventHandler PropertyChanged;

         protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
         {
             PropertyChangedEventHandler handler = PropertyChanged;
             if (handler != null) handler(this, new PropertyChangedEventArgs(propertyName));
         }