c＃ - 将对象添加到列表中的特定索引

Question

我一直花费数小时来找到一种方法将项目插入到我的列表中的对象。 这就是我所做的。

data = await (from iw in _context.InvestorWallets 
           join m in memberdata on iw.investorid equals m.id 
           where _context.InvestorDeposit.Any(item => item.investordepositid == iw.transactionid) || 
          _context.InvestorWithdrawal.Any(item => item.withdrawalid == iw.transactionid) || 
          _context.InstallmentPaymentDistribution.Any(item => item.paymentdistributionid == iw.transactionid) 
           select new InvestorWalletsViewModel() 
           { 
            username = m.userName, 
            fullname = m.fullName, 
            isActive = m.isActive, 
            memberType = m.memberType, 
            memberTypeName = m.memberTypeName, 
            emailAddress = m.emailAddress, 
            trxdate = iw.trxdate, 
            trxdesc = iw.trxdesc, 
            debit = iw.acounttype.ToLower() == "db" ? iw.amount : 0, 
            credit = iw.acounttype.ToLower() == "cr" ? iw.amount : 0, 
            investorid = iw.investorid, 
            investorwalletid = iw.investorwalletid, 
            transactiontype = 
            (
             iw.transactiontype.ToLower() == "dep" ? "Deposit" : 
             iw.transactiontype.ToLower() == "wit" ? "Withdrawal" : 
             iw.transactiontype.ToLower() == "rep" ? "IB-1610043 - Repayment" : "REGULER" 
            ), 
            paymentdistributionid = 
            (
             iw.transactiontype.ToLower() == "rep" ? iw.transactionid??0 : 0 
            ), 
            details = new List<InvestorWalletsViewModelDetail>(), // <-- I want to insert some object to this list 
            previousbalance = iw.previousbalance 
           }).Distinct().ToListAsync(); 

//This is to retrieve data from another table, based on data 
var data2 = (from i in _context.InstallmentPaymentDistributionDetails.Where(p => p.amount > 0) 
          where data.Any(d => d.paymentdistributionid == i.paymentdistributionid) 
          select i).Distinct().ToList(); 

//I used ForEach to itterate through the List, and fill the object 
data2.ForEach(d => 
{ 
    var x = data.Find(z => z.paymentdistributionid == d.paymentdistributionid); 
    if (x == null) return; 

//This is where I insert the value to the List 
    x.details.Add(new InvestorWalletsViewModelDetail //This code right here, it insert the value to all rows in the List, i just want to add the value to the specific row in the List 
    { 
     actualpayment = d.amount, 
     installmentfeetype_name = d.installmentfeetype_name 
    }); 
}); 

}

正如你可以在我的的ForEach看，我插入值的细节（内部列表列表）。但是，最主要的是，它确实将值插入到列表中，但它将值插入列表中的值为ALL，因为它只应将值插入到特定的行/索引中。我只是想将该值插入列表中的特定行。

Anyhelp可以理解的家伙，

感谢

Answer 1

难道你列表转换到一个ArrayList，然后使用内置的方法在给定索引处插入。

ArrayList arrayList = new ArrayList(list); 
arrayList.insert(index, val); 

Answer 2

如何使用Skip（）和Take（）？

你跳过你想省略的行数，然后取1个元素。这将返回一个包含一个元素的对象列表。

int yourRowIndex = 47; // just an example 
x.details.Skip(yourRowIndex).Take(1).ToList().Add(new InvestorWalletsViewModelDetail 
{ 
    actualpayment = d.amount, 
    installmentfeetype_name = d.installmentfeetype_name 
}); 

可能不需要ToList（）扩展。