[RESOLVED] When creating multiple datagridview controls at runtime, how do you hide columns?

I am having some trouble with hiding columns in a datagridview control that I am generating at runtime. I am generating that control inside of a runtime generated tab page in an existing tab control. My code is as follows:

Code:

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Try
    Do
        If m_DataTable.Columns.Contains("Checkpoint " & intCheckPointNumber & " Time") Then
            Dim tabNewCheckpoint As New TabPage
            Dim dgvNewCheckpoint As New DataGridView

            tabNewCheckpoint.Name = "tabCheckpoint" & intCheckPointNumber
            tabNewCheckpoint.Text = "Checkpoint " & intCheckPointNumber
            tabctrlTimingTable.TabPages.Add(tabNewCheckpoint)

            dgvNewCheckpoint.Name = "dgvCheckpoint" & intCheckPointNumber
            dgvNewCheckpoint.DataSource = m_DataTable
            dgvNewCheckpoint.Size = dgvTimingP2P.Size
            tabNewCheckpoint.Controls.Add(dgvNewCheckpoint)

            Try
                strColumnName = "Checkpoint " & intCheckPointNumber
                For Each col As DataColumn In m_DataTable.Columns
                    MessageBox.Show(col.ColumnName)
                    If col.ColumnName.StartsWith("Checkpoint") Then
                        If Not col.ColumnName.StartsWith(strColumnName) Then
                            dgvNewCheckpoint.Columns(col.ColumnName).Visible = False
                        End If
                    End If
                Next
            Catch
                MessageBox.Show(ErrorToString)
            End Try
        Else
            Exit Do
        End If
        intCheckPointNumber += 1
    Loop
Catch ex As Exception
    'MessageBox.Show(ErrorToString)
End Try

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The col.ColumnName value does directly correspond to the columns in the database, but an error is generated immediately upon this line:

Code:

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dgvNewCheckpoint.Columns(col.ColumnName).Visible = False

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The error that I keep getting is: "Object reference not set to an instance of an object"

This code works fine for a datagridview control that I have inside of another tab page in the tab control that were all created at design time.

Is there a problem with trying to hide the columns immediately after I have created the runtime generated datagridview?

I am using VB2010.

Thanks

my guess is that the column doesn't have the name you think it has.
try using the columnindex instead of the name.

No. There's a problem with you not adding columns to the DGV correctly (or at all?) At least that's what I'm assuming without the relevant code to check. Declare a New DataGridViewColumn (I think that's the right nomenclature, I'm flying blind at the moment. Assign values to it properties. Add it to the DGV. Then do the same all over again for each other column.

Quote:

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Originally Posted by dunfiddlin

No. There's a problem with you not adding columns to the DGV correctly (or at all?) At least that's what I'm assuming without the relevant code to check. Declare a New DataGridViewColumn (I think that's the right nomenclature, I'm flying blind at the moment. Assign values to it properties. Add it to the DGV. Then do the same all over again for each other column.

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No. the OP has set the datasource for the dgv which creates the columns, but they aren't named as the OP is expecting...

How can I find the column index with this For...Next loop? It is not a method of col at this point...

Quote:

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Originally Posted by .paul.

No. the OP has set the datasource for the dgv which creates the columns, but they aren't named as the OP is expecting...

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Oh right. Missed that line. Should've gone to Specsavers!

Aha! I figured it out. I had to move the following line:

Code:

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tabNewCheckpoint.Controls.Add(dgvNewCheckpoint)

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immediately below the following line:

Code:

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tabctrlTimingTable.TabPages.Add(tabNewCheckpoint)

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Wow, what a struggle! Thanks for your help though!