How to resolved Null Reference Exception in Linq edit query?

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C#

.NET

WPF

LINQ

Hello,

I am using this code for edit in wpf datagrid, but it getting error of null reference exception but data (SNo) is already filled in datagrid.

private void btnEdit_Click(object sender, RoutedEventArgs e)
{
InvoiceRecordsDataContext dataContext = new InvoiceRecordsDataContext();
InvoiceRecord irRow = dgInvoiceRecord.SelectedItem as InvoiceRecord;
int m = irRow.SNo;"error its getting "Null Reference Exception"
InvoiceRecord ir = (from p in dataContext.InvoiceRecords
where p.SNo == irRow.SNo
select p).Single();
ir.ProjectDetail = irRow.ProjectDetail;
ir.InvoiceDetail = irRow.InvoiceDetail;
ir.MilestonePercentage = irRow.MilestonePercentage;
ir.Amount = irRow.Amount;
dataContext.SubmitChanges();
MessageBox.Show("Row Updated Successfully.");
DisplayInvoiceRecords();
}
Please help me.

Thanks in Advance.

Ankit Agarwal
Software Engineer