ShoppingListViewModel.cs

using Margo.Data;
using Margo.UI.Utilities;
using System;
using System.Data;

namespace Margo.UI.ViewModel
{
    public class ShoppingListViewModel : BaseViewModel
    {
        private DataAccess _dataAccess = new DataAccess();
        private DataTable _shoppingList;

        public BaseViewModel ViewModel { get; set; }

        public DataTable ShoppingList
        {
            get { return _shoppingList; }
            private set
            {
                _shoppingList = value;
                OnPropertyChanged(nameof(ShoppingList));
            }
        }

        public RelayCommand AddProductCommand { get; private set; }

        public ShoppingListViewModel()
        {
            _dataAccess.ConnectToDatabase();
            ShoppingList = _dataAccess.ShoppingList;
            AddProductCommand = new RelayCommand(OnAddProduct);
        }

        public event Action AddProductRequested = delegate { };

        private void OnAddProduct()
        {
            AddProductRequested();
        }
    }
}