public void InsertOrUpdate(Product product)
 {
     if (product.ProductId == default(int)) {
         // New entity
         context.Products.Add(product);
     } else {
         // Existing entity
         context.Entry(product).State = EntityState.Modified;
     }
 }
 public void Update(Product product)
 {
     throw new NotImplementedException();
 }
 public List<Product> Find(Product product)
 {
     throw new NotImplementedException();
 }
 public int Add(Product product)
 {
     _Context.Products.Add(product);
     return product.ProductId;
 }