I have a data grid view bound to a data view. I'd like the failed validation effect for the user to be the same whether it comes from the underlying data table's column changing event or the DataGridView's DataError event -- to set an error provider on the cell and let them deal with it in thier own way.

In the DataError event while I can set the ErrorText, it doesn't appear to do anything at all -- the user is still "trapped" in the cell with the error. All the examples I've been able to find display a message box. Is it possible to set the error text in the cell and advance the focus to the next logical cell?

Thanks, and if any MS folks read this the new grid is a huge improvement over the old one.

Alan

Do you try set e.cancel=false after you set the ErrorText?

Canceling the textbox’s Validating event prevents the focus from leaving the textbox. 

This forces the user to enter good data into the textbox in order to continue.

From the lack of replies apparently you can't change the way that Data Error works, which is a real shame.

<Rant>

The existing behaviour, IMHO, makes it more difficult to do a proper three tier architecture...

The way it used to work, one could have the data table / data set in the middle tier, and perform all the data validation in the data column changing & row changing events of the data table. That way, no matter how many different presentations existed, they could all share the same validation logic. Now with some of the error handling in the Data Error event,and some of the error handling in data column changing and row changing, the distinction between which tier is responsible for what blurs a little.

Trapping the user is a good way to get a three finger restart. By trapping the user I mean putting him/her in a situation where s/he must deal with an error before focus can advance to the next control. That is, however, exactly how the data error thinking goes, the system says "This column is a number, and thou shalt type in a number and that's final."

</Rant>

Oh well!

Do you try set e.cancel=false after you set the ErrorText?

Canceling the textbox’s Validating event prevents the focus from leaving the textbox. 

This forces the user to enter good data into the textbox in order to continue.

Wang

That works for most errors so good answer...But I think the problem occurs farther up the sink chain (or message pump queue)...

I believe the issue is that the underlying data source column is an Int32, so if the user types 1.5 in the grid cell the type converter built into the grid's formatting routines can't coerce that into an integer, and that is what is calling the DataError event, so by the time one gets to that event no cancellation is possible.

A work around would be to create an unbound string column on the fly, move the ints to the string column, and move the string into the Int column when the row change committs... but what the user's want is:

They type whatever they want into the cell.

If it's wrong they get an error provider.

If there's an error provider the new value is not committed to the data store until corrected.

Is it possible to over-ride the behaviour of the default type converter?

Alan

From the lack of replies apparently you can't change the way that Data Error works, which is a real shame.

<Rant>

The existing behaviour, IMHO, makes it more difficult to do a proper three tier architecture...

The way it used to work, one could have the data table / data set in the middle tier, and perform all the data validation in the data column changing & row changing events of the data table. That way, no matter how many different presentations existed, they could all share the same validation logic. Now with some of the error handling in the Data Error event,and some of the error handling in data column changing and row changing, the distinction between which tier is responsible for what blurs a little.

Trapping the user is a good way to get a three finger restart. By trapping the user I mean putting him/her in a situation where s/he must deal with an error before focus can advance to the next control. That is, however, exactly how the data error thinking goes, the system says "This column is a number, and thou shalt type in a number and that's final."

</Rant>

Oh well!

Hi Alan.

I have a problem like yours.

I set the ErrorText but it doesn't appearand the user is still "trapped" in the cell without any message.

regards

Andrea

I don't know if this will help guy's but I use this in the DataError event:

((DataGridView)sender).CancelEdit();

after the error if the user removes focus from the row the data is discarded.

That could be a good idea. Display an error, let the user focus another cell, and set the original value.

Thanks! I tried this idea in vb.net and it works

Here is the code snipet in vb.net

e.ThrowException =

False

Dim v As DataGridView = CType(sender, DataGridView)

v.Rows(e.RowIndex).Cells(e.ColumnIndex).ErrorText =

"The value entered was wrong. The original value is reset"

v.CancelEdit()

Hi ,

I have an integer column in DataGridView and i dont want to CancelEdit when the user enternon numirical value, insted i need to force error icon to apear after

e.ThrowException = False

how can i do it??

My code is:

 Private Sub DataGridView1_CellValidating(ByVal sender As Object,  _ 
ByVal e As DataGridViewCellValidatingEventArgs)  _ 
Handles DataGridView1.CellValidating

        If DataGridView1.Columns(e.ColumnIndex).Name = "NumiricText1" Then
                       Me.DataGridView1.Rows(e.RowIndex).ErrorText = ""
            Dim newInteger As Integer

             If DataGridView1.Rows(e.RowIndex).IsNewRow Then Return
            If Not Integer.TryParse(e.FormattedValue.ToString(), newInteger) _
                OrElse newInteger < 0 Then
                e.Cancel = True
                Me.DataGridView1.Rows(e.RowIndex).ErrorText = "the value must be a non-negative integer"
            End If

        End If

    End Sub

Private Sub DataGridView1_DataError(ByVal sender As Object, _
 ByVal e As System.Windows.Forms.DataGridViewDataErrorEventArgs) _
 Handles DataGridView1.DataError

        e.ThrowException = False

End Sub