我要处理大量的IBM i数据，而不能使用EF来处理这些数据。因此，我改为执行以下操作：
DataTable dt = new DataTable();
using (iDB2Connection conn = new iDB2Connection(_connString))
{
using (iDB2Command cmd = new iDB2Command(sb.ToString(), conn))
{
conn.Open();
using (iDB2DataAdapter da = new iDB2DataAdapter(cmd)) { da.Fill(dt); }
conn.Close();
}
}
从那里，我可以通过以下方式对数据建模：
var billHistory = from i in dt.AsEnumerable()
select new BillHistory
{
CustomerId = i.Field<int>("CCUSTN"),
DueDate = Convert.ToDateTime(i.Field<decimal>("CDUEDT").ToString("0000-00-00")),
Type = i.Field<string>("CTYPE"),
RunDate = Convert.ToDateTime(i.Field<decimal>("CDTRUN").ToString("0000-00-00")),
MeterReadDate = Convert.ToDateTime(i.Field<decimal>("CDREAD").ToString("0000-00-00")),
PreviousReadDate = Convert.ToDateTime(i.Field<decimal>("CPREVD").ToString("0000-00-00")),
DaysBetweenReads = i.Field<int>("CDAYS"),
BillSendDate = Convert.ToDateTime(i.Field<decimal>("CDSENT").ToString("0000-00-00")),
Meter1Reading = i.Field<int>("CMETR1"),
Meter2Reading = (i.Field<int>("CMETR2") == 0) ? null : i.Field<int?>("CMETR2"),
ConsumptionInUnits = i.Field<int>("CCONSU"),
PreviousReading = i.Field<int>("CPREV1"),
AverageUnitsOver3Months = i.Field<int>("CAVG3M"),
LastMonthUnits = i.Field<int>("CUNT1M"),
PercentChange = i.Field<int>("CPCTCH"),
IsEstimated = (i.Field<string>("CESTIM") == "Y") ? true : false,
IsFinalBill = (i.Field<string>("CFINAL") == "Y") ? true : false,
SprinklerLocation = (i.Field<int>("CSPRLO") == 0) ? null : i.Field<int?>("CSPRLO"),
SprinklerReading = (i.Field<int>("CSPRMETR") == 0) ? null : i.Field<int?>("CSPRMETR"),
SprinklerConsumptionInUnits = (i.Field<int>("CSPRCONSU") == 0) ? null : i.Field<int?>("CSPRCONSU"),
SprinklerPreviousReading = (i.Field<int>("CSPRPREV1") == 0) ? null : i.Field<int?>("CSPRPREV1"),
SprinklerAverageUnitsOver3Months = (i.Field<int>("CSPRAVG3M") == 0) ? null : i.Field<int?>("CSPRAVG3M"),
SprinklerLastMonthUnits = (i.Field<int>("CSPRUNT1M") == 0) ? null : i.Field<int?>("CSPRUNT1M"),
SprinklerPercentChange = (i.Field<int>("CSPRPCT") == 0) ? null : i.Field<int?>("CSPRPCT"),
PreviousBalance = (i.Field<decimal>("CPREVS") == 0) ? null : i.Field<decimal?>("CPREVS"),
PaymentAdjustment = (i.Field<decimal>("CPAYAD") == 0) ? null : i.Field<decimal?>("CPAYAD"),
WaterCost = (i.Field<decimal>("CWATER") == 0) ? null : i.Field<decimal?>("CWATER"),
SewerCost = (i.Field<decimal>("CSEWER") == 0) ? null : i.Field<decimal?>("CSEWER"),
RefuseCost = (i.Field<decimal>("CREFUS") == 0) ? null : i.Field<decimal?>("CREFUS"),
LawnSprinklerCost = (i.Field<decimal>("CLAWNS") == 0) ? null : i.Field<decimal?>("CLAWNS"),
ACCost = (i.Field<decimal>("CAIR") == 0) ? null : i.Field<decimal?>("CAIR"),
FireLineCost = (i.Field<decimal>("CFIREL") == 0) ? null : i.Field<decimal?>("CFIREL"),
HydrantCost = (i.Field<decimal>("CHYDRA") == 0) ? null : i.Field<decimal?>("CHYDRA"),
StormWaterCost = (i.Field<decimal>("CSTORM") == 0) ? null : i.Field<decimal?>("CSTORM"),
SpecialBillTaxable = (i.Field<decimal>("CSPECT") == 0) ? null : i.Field<decimal?>("CSPECT"),
SpecialBillNonTaxable = (i.Field<decimal>("CSPECN") == 0) ? null : i.Field<decimal?>("CSPECN"),
StateTax = (i.Field<decimal>("CSTTAX") == 0) ? null : i.Field<decimal?>("CSTTAX"),
RefuseTax = (i.Field<decimal>("CRFTAX") == 0) ? null : i.Field<decimal?>("CRFTAX"),
StateConnectionFee = (i.Field<decimal>("CSCFEE") == 0) ? null : i.Field<decimal?>("CSCFEE"),
CityTax = (i.Field<decimal>("CCITAX") == 0) ? null : i.Field<decimal?>("CCITAX"),
ACHCredit = (i.Field<decimal>("CACHCR") == 0) ? null : i.Field<decimal?>("CACHCR"),
PaperlessCredit = (i.Field<decimal>("CPPLCR") == 0) ? null : i.Field<decimal?>("CPPLCR"),
OneTimeDescription = (i.Field<string>("C1XDES") == String.Empty) ? null : i.Field<string>("C1XDES"),
OneTimeCredit = (i.Field<decimal>("C1XAMT") == 0) ? null : i.Field<decimal?>("C1XAMT"),
LateFee = (i.Field<decimal>("CLATFE") == 0) ? null : i.Field<decimal?>("CLATFE"),
NSFFee = (i.Field<decimal>("CNSFFE") == 0) ? null : i.Field<decimal?>("CNSFFE"),
TotalBill = (i.Field<decimal>("TOTAL_BILL") == 0) ? null : i.Field<decimal?>("TOTAL_BILL")
};
这是确切的复制粘贴（很抱歉，长度不正确）。真正的问题出在我有
InvalidCastException的时候，我该如何去发现问题？过去，我已经慢慢找到了它们，但是我希望有更好的方法。这是异常详细信息：
System.InvalidCastException was unhandled
Message=Specified cast is not valid.
Source=System.Data.DataSetExtensions
StackTrace:
at System.Data.DataRowExtensions.UnboxT`1.ValueField(Object value)
at System.Data.DataRowExtensions.Field[T](DataRow row, String columnName)
at SendToInternet.Model.IbmIDatabase.<GetCustomerHistory>b__11(DataRow i) in C:\Documents and Settings\ispa2\My Documents\Visual Studio 2010\Projects\SendToInternet\SendToInternet\Model\IbmIDatabase.cs:line 514
at System.Linq.Enumerable.WhereSelectEnumerableIterator`2.MoveNext()
at SendToInternet.Controllers.UtilityBillController.ProcessAllUtilityBills() in C:\Documents and Settings\ispa2\My Documents\Visual Studio 2010\Projects\SendToInternet\SendToInternet\Controllers\UtilityBillController.cs:line 131
at SendToInternet.Program.Main(String[] args) in C:\Documents and Settings\ispa2\My Documents\Visual Studio 2010\Projects\SendToInternet\SendToInternet\Program.cs:line 59
at System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly, String[] args)
at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)
at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean ignoreSyncCtx)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
at System.Threading.ThreadHelper.ThreadStart()
InnerException:
第514行是
var billHistory = from i in dt.AsEnumerable()，它没有用。除非b__11是，但是我仍然看不到那里或附近的任何问题。 最佳答案
如果您查看InvalidCastException的文本，它将在其中包含一个行号。它提到的行号是InvalidCastException的来源。