错误索引超出范围。 必须是非负数且小于集合的大小

Question

我想用for填充我的DTO对象，但是我收到了这个错误：

Index was out of range. Must be non-negative and less than the size of the collection

这是我的代码：

 public static List <BankDepositHistoryDTO> DtoTODomain()
        {
            MyketAdsEntities context = new MyketAdsEntities();
            List<BankDepositHistoryDTO> bdto = new List<BankDepositHistoryDTO>();


            //var transactionlist


            var transactionlist = GetListoftransactions.GetAccountingListoftransactions();
            for (int i = 0; i < transactionlist.Count; i++)
            {
                bdto[i].AccountId = transactionlist[i].AccountId;
                bdto[i].Id = transactionlist[i].Id;
                bdto[i].Amount = transactionlist[i].Amount;
                bdto[i].AdditionalData = transactionlist[i].AdditionalData;
                bdto[i].ClientIp = transactionlist[i].ClientIp;
                bdto[i].Gateway = transactionlist[i].Gateway;
                bdto[i].PaymentRefNumber = transactionlist[i].PaymentRefNumber;
                bdto[i].ReturnUrl = transactionlist[i].ReturnUrl;
                bdto[i].State = transactionlist[i].State;
                bdto[i].Uuid = transactionlist[i].Uuid;



            }
            return bdto;

        }

我在这里收到了这条消息

bdto[i].AccountId = transactionlist[i].AccountId;

Answer 1

您已创建一个空列表，但未向其添加元素。 您必须先添加一个元素，然后更新其属性：

for (int i = 0; i < transactionlist.Count; i++)
{
    BankDepositHistoryDTO b = new BankDepositHistoryDTO();
    b.AccountId = transactionlist[i].AccountId;
    b.Id = transactionlist[i].Id;b
    b.Amount = transactionlist[i].Amount;
    b.AdditionalData = transactionlist[i].AdditionalData;
    b.ClientIp = transactionlist[i].ClientIp;
    b.Gateway = transactionlist[i].Gateway;
    b.PaymentRefNumber = transactionlist[i].PaymentRefNumber;
    b.ReturnUrl = transactionlist[i].ReturnUrl;
    b.State = transactionlist[i].State;
    b.Uuid = transactionlist[i].Uuid;
    bdto.Add(b);
}

Answer 2

好吧， bdto长度小于transactionlist长度。

在for循环之前，您可以调整bdto大小以匹配transactionlist

Answer 3

我完全同意@Ashkan和@Mureinik的回答，但只是为了改进代码，你可以使用AutoMapper 。 它将减少每个元素的循环和迭代。 似乎这两个对象之间的所有属性都是相同的。

Mapper.CreateMap<Transaction,BankDepositHistoryDTO>(); 
BankDepositHistoryDTO obj = Mapper.Map<Transaction,BankDepositHistoryDTO>(TransactionObj);

另外如果GetListoftransactions.GetAccountingListoftransactions(); 返回List<BankDepositHistoryDTO> ，可以直接在方法中返回该对象。