public ActionResult <IEnumerable <CustomerViewDTO> > MyProductsAndReviews([FromQuery] string email) // Don't do this in a real app! { var customer = _repository.GetFullyLoadedCustomer(email); if (customer == null) { Console.WriteLine("Returning empty list"); return(Ok(null)); } var productMapping = customer .Products .Select(cp => cp.Product) .Select(product => new CustomerViewDTO { Product = product, Review = product.Reviews.SingleOrDefault(r => r.CustomerId == customer.CustomerId) }).ToList(); return(productMapping); }