/// <summary> /// Find all invoices of one Customer. /// </summary> /// <param name="email"></param> /// <returns></returns> public IEnumerable <InvoiceDTO> FindInvoices(string email) { AccountDTO customer = new AccountDTO(); customer = AB.FindBy(email); IEnumerable <InvoiceDTO> result = new List <InvoiceDTO>(); if (customer != null) { result = DB.FindByCustomer(customer.GetID()); } return(result); }