Datagrid - How to Undo a delete

  • Thread starter Thread starter DanB
  • Start date Start date
D

DanB

I want to asked the user if he is sure before deleting a row in a datagrid.

I've created an event handler for the underlying table using the RowDeleting
Event.

If the user responds that he does not want to delete the row then I think I
am supposed to throw an exception.

But the rowstate is changed to deleted anyway. I thought throwing the
exception would prevent this.

What am I doing wrong?

Dan
 
DanB said:
I want to asked the user if he is sure before deleting a row in a datagrid.

I've created an event handler for the underlying table using the RowDeleting
Event.

If the user responds that he does not want to delete the row then I think I
am supposed to throw an exception.

But the rowstate is changed to deleted anyway. I thought throwing the
exception would prevent this.

What am I doing wrong?

Dan
Click to expand...

You might be able to call RejectChanges on the row in question, but I have
to admit, I have not tried this approach...

Best Regards,

Andy
 
I think that will ultimately be the answer. But I Tried
Try

If MsgBox(strPrompt, MsgBoxStyle.YesNo, "Deletion Requested") =
MsgBoxResult.No Then

Throw New Exception("Row was not deleted")

End If

Exit Sub

Catch ex As Exception

MsgBox("Data not deleted")

e.Row.RejectChanges()

End Try


Where e = DataRowChangeEventArgs

And this is either ignored or the actual deletion occurs after the Catch
phrase is executed.
 
DanB said:
And this is either ignored or the actual deletion occurs after the Catch
phrase is executed.
Click to expand...

I'm not sure why it wouldn't work then. Maybe there is a deep copy of the
row made internally, and the reject basically does nothing?

At this point all I can suggest is to try and get the UI confirmation
somewhere earlier in the "food chain".

Best Regards,

Andy
 
Hi,

Here is some sample code on how to create an inherited datagrid
which has a row deleted event.

http://www.onteorasoftware.com/downloads/delete.zip

Ken
---------------------
I want to asked the user if he is sure before deleting a row in a datagrid.

I've created an event handler for the underlying table using the RowDeleting
Event.

If the user responds that he does not want to delete the row then I think I
am supposed to throw an exception.

But the rowstate is changed to deleted anyway. I thought throwing the
exception would prevent this.

What am I doing wrong?

Dan
 
I am not sure this is the best answer, but it worked for me.
I had the problem with Whidbey's new dataset methodology. I am creating
an input form.
Deleting a specific record is not allowed if the record is referenced.
I could not stop the update, but I did reverse it as follows:
------------------------
Private mAllowDelete As Boolean = False
Private Sub BeforePersonDeletion(ByVal sender As Object, ByVal e As
System.Data.DataRowChangeEventArgs)
'Reverse the deletion of a row.
Dim curRow As PersonRow = CType(e.Row, PersonRow)
Stop
mAllowDelete = DLookup("DocAuthor", "Doc", "DocAuthor=" +
curRow.ID.ToString, mCn) Is Nothing
If Not mAllowDelete Then
MsgBox("You cannot delete this person, he is the author of a
document in the database")
End If
End Sub
Private Sub AfterPersonDeletion(ByVal sender As Object, ByVal e As
System.Data.DataRowChangeEventArgs)
'Undo if we should not have deleted
If Not mAllowDelete Then
e.Row.RejectChanges()
End If
End Sub
 
This almost works :D

When I do the first Delete, and click NO , it doesnt delete, but then, if I
click on another row, it deletes that row - with no notification.

wild eh.

I agree Dan, I thought it would be easier than this. I have been struggling
with a confirmation on the delete for a while now, the MS site says
just use a simple dataTable.RejectChanges on a RowDeleting event - that
didn't work, the DataGrid still reflected the delete.

Then - elsewhere - they say 'throw an exception' - ok, tried that - it
still didnt keep the DG from removing the row. (yes, I have tried a number of
other techniques)

This one looks most promising
 
Back
Top