VB.Net datagridview, need to set some columns automatically when user inserts a new row

Bernard Thouin
Bernard Thouin used Ask the Experts™
on
Hi

I have developed a number of console apps, but this is my first Windows forms-based app, with a DataGridView control (which is showing the data in a datatable) where users can add rows. When they insert a new row, I want to set some columns of that row automatically (insertion date/time, user name, that kind of stuff).

I don't knw how to do that... Can you help ?

Thanks
Bernard
Comment
Watch Question

Do more with

Expert Office
EXPERT OFFICE® is a registered trademark of EXPERTS EXCHANGE®
I use the .CurrentCellChanged event handler (blnLoading is set at the start of the Load event and turned off at the end of Load, so if the routine is triggered during that time, it's simply ignored):

    
Private Sub dgvChoices_CurrentCellChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles dgvChoices.CurrentCellChanged
        If blnLoading = False AndAlso Not dgvChoices.CurrentCell Is Nothing Then   
            Dim drChoice As dsAN.ChoicesRow = DirectCast(dvwChoices(dgvChoices.CurrentRow.Index).Row, dsAN.ChoicesRow)
            If drChoice.IsfldDateNull Then
                drChoice.fldDate = Date.Today
            End If
            If drChoice.IsfldChoiceNull Then
                drChoice.fldChoice = ""
            End If
        End If
    End Sub

Open in new window


The key here is that at least one of the fields in the newly created row is null, or in some other way it's evident that the row is new and not properly initialized. If you get a match on that when .CurrentCellChanged, use that as the flag to change the other fields.
Infotrakker Software
Most Valuable Expert 2012
Top Expert 2014
Commented:
If you need to do this ONLY when the user is in the "new row", you can check the RowEntered event and determine if they're on a new row:

if e.RowIndex = YourDataGridView.NewRowIndex Then
  >> modify your row cells here:
  YourDataGridView.Rows(e.RowIndex).Cells("YourCellName").Value = SomeValue
End If

You could also set the DefaultCellStyle.NullValue property of your DGV column:

YourDataGridView.Columns(ColIndex).DefaultCellStyle.NullValue = SomeValue

If you're using a Datatable to fill the grid, you can also set the Default Value of a DAtaColumn.

Finally, there's the DefaultVlauesNeeded event for your DGV. You can set Default Values for New Rows there:

Private Sub YourDataGridView_DefaultValuesNeeded(ByVal sender As Object, ByVal e As System.Windows.Forms.DataGridViewRowEventArgs) Handles YourDataGridView.DefaultValuesNeeded
        e.Row.Cells("YourCellName ").Value = "SomeValue"
    End Sub
Bernard ThouinIT Analyst and developer

Author

Commented:
Hi Scott

Thanks a lot, it works fine.

Just one thing I first stumbled on: why is the cell name = <datatable column name> & "DataGridViewTextBoxColumn", instead of just  being the datatable column name ? ?
OWASP Proactive Controls

Learn the most important control and control categories that every architect and developer should include in their projects.

Scott McDaniel (EE MVE )Infotrakker Software
Most Valuable Expert 2012
Top Expert 2014

Commented:
If you "autobind" a DataGridView to a Datatable, the DGV cells should be named the same as your DataTable columns. For example, if my datatable has a column named "CustomerName", by DGV should contain a column named "CustomerName" as well.
Bernard ThouinIT Analyst and developer

Author

Commented:
Well I defined a dataset, linked it to the form in my app, then added the grid view and set it datasource to be one of the datatables in the dataset, I don't know if that is what you call autobinding, but the result is that the column names are starting with the "real" column name but then this "DataGridViewTextBoxColumn" gets appended to it.

I found out because I got an error telling me the column name <datatable column name> could not be found in the <MyGrid>.Rows(e.RowIndex).Cells("<datatable colum name>") statement, so I debugged and printed out the used column name.
Scott McDaniel (EE MVE )Infotrakker Software
Most Valuable Expert 2012
Top Expert 2014

Commented:
That's odd, and I'm not sure why that would occur. When I bind my DGV to a Datatable, the columns names are exactly the same as those of the Datatable.

I don't generally use Datasets, however. I'm curious if that's the reason.
Bernard ThouinIT Analyst and developer

Author

Commented:
I'm using VS2013, maybe that also makes a difference ?

Anyway, it works fine that's the main thing, you get the points, thanks a lot :-)

Bernard

Do more with

Expert Office
Submit tech questions to Ask the Experts™ at any time to receive solutions, advice, and new ideas from leading industry professionals.

Start 7-Day Free Trial