[2008] DataGridView and adding Rows

[Psychlotron]

I'm having a problem adding rows to a datagridview. I'm sure its just a stupid oversight on my part, but I just can't figure what.

So, I have a datagridview with allowusertoaddrows = false and autogeneratecolumns = false and some columns defined (as in following example). I create a new datagridviewrow and add it to the datagridview and it picks up the cells just fine, but it has a rowindex of -1. So when I try to set the value of one of the cells in the row, i get an error, objectoutofrangeexception, because the rowindex is -1.

How do I create a row and set the values in the row after adding it to the datagridview? Here is some code to replicate the problem.

I've replicated my problem with the following code (just add a datagridview to a new windows form project):

Dim newCollection As New List(Of Long)

    Private Sub Form1_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load

        Me.InitializeDataGridView1()

        Me.AddSomeItemsToList()

        Me.AddSomeRows()

    End Sub

    Friend Sub AddSomeItemsToList()
        For i As Integer = 1 To 5
            Me.newCollection.Add(i)
        Next
    End Sub

    Friend Sub AddSomeRows()
        Try

            For Each item As Long In Me.newCollection

                Dim newRow As New DataGridViewRow

                Me.DataGridView1.Rows.Add(newRow)

                newRow.Cells("clmTest").Value = CLng(item)

            Next

        Catch ex As Exception
            MessageBox.Show(ex.Message)
        End Try

    End Sub

    Friend Sub InitializeDataGridView1()

        With Me.DataGridView1
            .AutoGenerateColumns = False
            .AllowUserToAddRows = False

            If Not .Columns.Contains("clmTest") Then

                Dim clmTest As New DataGridViewTextBoxColumn

                With clmTest
                    .ValueType = GetType(Long)
                    .ReadOnly = True
                    .Width = 100
                    .DisplayIndex = 0
                    .HeaderText = "Test"
                    .Name = "clmTest"
                End With

                .Columns.Add(clmTest)
            End If

        End With

    End Sub

Thanks,
Jerome

[JstnRyan]

I think it has to do with the value of newRow persisting after your For...Loop, because the first row is fine, but it breaks on the second row. Something like this works though:

            For i = 1 To newCollection.Count
                DataGridView1.Rows.Add(1)
                DataGridView1.Rows(DataGridView1.Rows.Count - 1).Cells(0).Value = newCollection(i - 1)
            Next

[Psychlotron]

Thanks for your help. I can get the code to work, now, using your:

DataGridView1.Count -1

value as the index of the row. I don't really understand why the row that I add doesn't update its rowindex. You said it may have something to do with the newRow value persisting through loops, but I changed the structure so that it was setting the variable to nothing before it was reassigning the value, and it still didn't work.

I also tried using:

me.Datagridview1.rows.add()
dim newRowIndex as integer = me.DataGridView1.NewRowIndex
me.datagridview1.rows(newRowIndex).cells("clmTest").value = ...

but it was setting the newRowIndex value to be -1.

So I got things working, but I don't understand why the "built in" procedures aren't working like it SEEMS they ought to be.

Any ideas?

Thanks,
Jerome