Null Reference Exception while adding new Row to DataTable

Question

I'm having this strange issue while adding a new row to a DataTable. It does not occur every time, but while running the application, I get null reference exception while there are no objects found null.

Here is the code:

Firstly Clear the Row and Columns of the DataTable:

dtLibraries.Rows.Clear();
dtLibraries.Columns.Clear();
dtLibraries.Columns.Add("Col1");
dtLibraries.Columns.Add("Col2");
dtLibraries.Columns.Add("Col3");
dtLibraries.Columns.Add("Col4");
dtLibraries.Columns.Add("Col5");
dtLibraries.Columns.Add("Col6");
dtLibraries.Columns.Add("Col7");
dtLibraries.Columns.Add("Col8");
dtLibraries.Columns.Add("Col9");

Then reading another DataTable and Writing Data to this table:

for (int s = 0; s <= dttemp.Rows.Count - 1; s++)
{
    dttemp1.Clear();
    dttemp1 = business.GetOutputLibraries("SimObjectOutputRequestSet",
    dttemp.Rows[s].ItemArray[2].ToString(),
    dttemp.Rows[s].ItemArray[1].ToString(), dttemp.Rows[s].ItemArray[0].ToString());

    for (int j = 0; j <= dttemp1.Rows.Count - 1; j++)
    {
        DataRow dr = dtLibraries.NewRow();
        dr["Col1"] = dttemp1.Rows[j].ItemArray[0].ToString();
        dr["Col2"] = dttemp1.Rows[j].ItemArray[1].ToString();
        dr["Col3"] = dttemp1.Rows[j].ItemArray[2].ToString();
        dr["Col4"] = dttemp.Rows[s].ItemArray[0].ToString();
        dr["Col5"] = dttemp.Rows[s].ItemArray[2].ToString();
        dr["Col6"] = dttemp.Rows[s].ItemArray[1].ToString();
        dr["Col7"] = cmbObject.Text.ToString();
        dr["Col8"] = cmbLibraryType.Text;
        dr["Col9"] = cmbLibrarySubType.Text;
        dtLibraries.Rows.Add(dr);  /// Exception occurs on this line
    }
}

StackTrace:

at System.Data.NameNode.Eval(DataRow row, DataRowVersion version)
   at System.Data.BinaryNode.EvalBinaryOp(Int32 op, ExpressionNode left, ExpressionNode right, DataRow row, DataRowVersion version, Int32[] recordNos)
   at System.Data.BinaryNode.Eval(DataRow row, DataRowVersion version)
   at System.Data.DataExpression.Invoke(DataRow row, DataRowVersion version)
   at System.Data.Index.AcceptRecord(Int32 record, IFilter filter)
   at System.Data.Index.ApplyChangeAction(Int32 record, Int32 action, Int32 changeRecord)
   at System.Data.Index.RecordStateChanged(Int32 record, DataViewRowState oldState, DataViewRowState newState)
   at System.Data.DataTable.RecordStateChanged(Int32 record1, DataViewRowState oldState1, DataViewRowState newState1, Int32 record2, DataViewRowState oldState2, DataViewRowState newState2)
   at System.Data.DataTable.SetNewRecordWorker(DataRow row, Int32 proposedRecord, DataRowAction action, Boolean isInMerge, Boolean suppressEnsurePropertyChanged, Int32 position, Boolean fireEvent, Exception& deferredException)
   at System.Data.DataTable.InsertRow(DataRow row, Int64 proposedID, Int32 pos, Boolean fireEvent)
   at System.Data.DataRowCollection.Add(DataRow row)

what is dttemp1?which line exactly rise the error execption? — Selalu_Ingin_Belajar, Nov 02 '12 at 07:30
your StackTrace doesn't has details like which method call raised exception, in which method exception occurred etc.. — dotNETbeginner, Nov 02 '12 at 07:33
@Selalu_Ingin_Belajar: it's another `DataTable`. I am converting that dataTable values to string, so i do not think that will cause error. — Niranjan Singh, Nov 02 '12 at 07:34
@dotNETbeginner: it's Exception strackTrace, i have remove the last line and that is not relevant to problem. — Niranjan Singh, Nov 02 '12 at 07:36
Why don't you step through the code and see on what line the exception occurs? It would help us help you (and at best, you'll find the answer by then) =) — Mario S, Nov 02 '12 at 07:36
Make sure that all data transfered from dttemp1 to dtLibraries satisfies any rowfilter on dtLibraries. — Andreas Sabroe Jydebjerg, Nov 02 '12 at 07:41
Almost all cases of NullReferenceException are the same. Please see "[What is a NullReferenceException in .NET?](http://stackoverflow.com/questions/4660142/what-is-a-nullreferenceexception-in-net)" for some hints. — John Saunders, Nov 02 '12 at 07:48
@Niranjan Kala - do you have a RowFilter on the dtLibraries DataTable? — Andreas Sabroe Jydebjerg, Nov 02 '12 at 07:48
@AndreasSabroeJydebjerg: There are no RowFilter on this table when we reloading data in it. — Niranjan Singh, Nov 02 '12 at 09:29
@Niranjan Kala: Can you show us the instantiation of dtLibraries? Are there fx. any primary key assigned? — Andreas Sabroe Jydebjerg, Nov 02 '12 at 10:06
@AndreasSabroeJydebjerg: `private DataTable dtLibraries = new DataTable();` just this as class level variable. — Niranjan Singh, Nov 02 '12 at 10:50

score 1 · Answer 1 · answered Nov 02 '12 at 07:44

1

it's from your schema :

dtLibraries.Columns.Add("Col1");
dtLibraries.Columns.Add("Col2");

you using Capital "C". meanwhile you call column with lowercase "c".

dr["col1"] = dttemp1.Rows[j].ItemArray[0].ToString();
dr["col2"] = dttemp1.Rows[j].ItemArray[1].ToString();

maybe that's the problem

answered Nov 02 '12 at 07:44

Selalu_Ingin_Belajar

365
2
6
20

Sorry for the typo, passed `column names` are already match with name of the column. this is not an issue. These lines will cause error before the line where i am specifying the error. – Niranjan Singh Nov 02 '12 at 07:59

score 1 · Accepted Answer · answered Nov 06 '12 at 10:32

1

As suggested by @AndreasSabroeJydebjerg, I have checked for the filters. May be that was causing problem with binding controls.

To make it work, i have loaded another table done all work around for this..

Thanks to all for suggestion.

answered Nov 06 '12 at 10:32

Niranjan Singh

17,209
2
39
70

Null Reference Exception while adding new Row to DataTable

2 Answers2