mvvm-community-demo/MvvmCommunityApp/viewmodels/MainWindowViewModel.cs

using CommunityToolkit.Mvvm.ComponentModel;
using CommunityToolkit.Mvvm.Input;
using System;

namespace MvvmCommunityApp.viewmodels
{
    public partial class MainWindowViewModel : ObservableObject
    {
        public string Title { get; set; }

        [ObservableProperty]
        private string _customer;

        public MainWindowViewModel()
        {
            Title = "MyIocName";
            //
        }

        [RelayCommand]
        private void Add()
        {
            Console.WriteLine("Do Add");
        }

        [RelayCommand]
        private void Update()
        {
            Customer = "New Customer";
        }
    }
}