问题
The following code:
foreach (DataRow fillRateDataRow in dtFillRateResults.Rows)
{
. . .
var frbdbc = new FillRateByDistributorByCustomer
{
ShortName = fillRateDataRow["ShortName"].ToString(),
Unit = fillRateDataRow["Unit"].ToString(),
CustNumber = fillRateDataRow["Custno"].ToString(),
MemberItemCode = fillRateDataRow["MemberItemCode"].ToString(),
Qty = Convert.ToInt32(fillRateDataRow["Qty"]),
QtyShipped = Convert.ToInt32(fillRateDataRow["QtyShipped"]),
ShipVariance = fillRateDataRow["ShipVariance"].ToString(),
CWeek = fillRateDataRow["CWeek"].ToString(),
PAItemCode = fillRateDataRow["PAItemCode"].ToString(),
PADescription = fillRateDataRow["PADescription"].ToString(),
TransactionType = fillRateDataRow["TransactionType"].ToString(),
SplitCase = fillRateDataRow["SplitCase"].ToString(),
ReasonCode = fillRateDataRow["ReasonCode"].ToString(),
ReasonDescription = fillRateDataRow["ReasonDescription"].ToString(),
CompanyName = fillRateDataRow["CompanyName"].ToString()
};
...fails once in a great while with, "Object cannot be cast from DBNull to other types. Exception Source: mscorlib Exception StackTrace: at System.DBNull.System.IConvertible.ToInt32(IFormatProvider provider) at System.Convert.ToInt32(Object value)"
So it seems that either Qty or QtyShipped are sometimes DBNull (the only int vals amidst a sea of strings).
Is there a way to say "if it's DBNull, assign 0 to the var" and thus avoid the exception?
回答1:
You can use a conditional expression:
QtyShipped = fillRateDataRow["QtyShipped"] != DBNull.Value ? Convert.ToInt32(fillRateDataRow["QtyShipped"]) : 0
If you need to do it a lot, making a helper method for this task would let you shrink your code for better readability.
回答2:
You can use this expression as well:
QtyShipped = fillRateDataRow.Field<int?>("QtyShipped") ?? 0;
来源:https://stackoverflow.com/questions/40411518/how-can-i-preempt-the-attempted-assignment-of-dbnull-to-an-int