错误索引超出范围。必须是非负数且小于集合的大小

Posted 2023-04-13

【中文标题】错误索引超出范围。必须是非负数且小于集合的大小

【英文标题】：Error Index was out of range. Must be non-negative and less than the size of the collection

【发布时间】：2019-08-28 13:46:12

【问题描述】：

我正在尝试用 for 填充我的 DTO 对象，但出现此错误：

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;

【参考方案1】：

您创建了一个空列表，并且没有向其中添加元素。你必须先添加一个元素，然后更新它的属性：

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);

【参考方案2】：

很明显，bdto 长度小于 transactionlist 长度。

在您的 for 循环之前，您可以调整 bdto 的大小以匹配 transactionlist

【参考方案3】：

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

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

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