public IActionResult CheckReturnBook() { var loans = _loan.GetAll(); List <LoanViewModel> listReturnBook = new List <LoanViewModel>(); foreach (var loan in loans) { listReturnBook.Add(new LoanViewModel { Book = _book.GetBookByLoanId(loan.LoanId), Member = _member.GetMemberByLoanId(loan.LoanId), Loan = _loan.GetById(loan.LoanId), Category = null }); } if (listReturnBook == null) { return(NotFound()); } return(View(listReturnBook)); }