How to resolve null reference exception in WinForms GridGrouping?

Resolve null reference exception

While changing the DataSource in the ComboBox cell in WinForms Grid Grouping, a null reference exception is raised. This is because the database is updated and then refreshed after you pick a value from a ComboBox cell by using the RecordValueChanged event. The newly edited value is not committed while the database updates. So, when you try to click on the next row, the RecordValueChanged event refreshes the database before the ComboBox commits the new value into the underlying database.

Figure 1: Null reference exception

This can be solved by calling the EndEdit() in the TableControlCurrentCellCloseDropDown event. Refer to the following code example.

C#

void gridGroupingControl1_TableControlCurrentCellCloseDropDown(object sender, GridTableControlPopupClosedEventArgs e)
{
   if(e.Inner.PopupCloseType == Syncfusion.Windows.Forms.PopupCloseType.Done)
   {
      // Commits value in the ComboBox manually.
      e.TableControl.CurrentCell.EndEdit();
   }
}

VB

Private Sub gridGroupingControl1_TableControlCurrentCellCloseDropDown(ByVal sender As Object, ByVal e As GridTableControlPopupClosedEventArgs)
   If e.Inner.PopupCloseType = Syncfusion.Windows.Forms.PopupCloseType.Done Then
      'Commits value in the ComboBox manually.
      e.TableControl.CurrentCell.EndEdit()
   End If
End Sub

Conclusion

I hope you enjoyed learning how to resolve null reference exceptions in WinForms GridGrouping.

You can refer to WinForms GridGrouping feature tour page to know about its other groundbreaking feature representations and documentation, and how to quickly get started for configuration specifications. You can also explore our WinForms GridGrouping example to understand how to create and manipulate data.

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