DatagridViewComboboxCell selectedindexchanged does not work

Question

I've been working in a project with VS2005 and VB.NET, in this project I have a DataGridView with 3 DataGridViewComboboxCell inside of it. What I have been trying to do is make it so that when the user selects a value from the first DataGridViewComboboxCell the value of the 2 other cells change. This is the code for that part:

Private Sub DataGridView1_EditingControlShowing(ByVal sender As System.Object, ByVal e         As System.Windows.Forms.DataGridViewEditingControlShowingEventArgs) Handles DataGridView1.EditingControlShowing

    If (TypeOf e.Control Is DataGridViewComboBoxEditingControl) AndAlso _
        DataGridView1.CurrentCell.ColumnIndex = 1 Then

        Dim cbo As ComboBox = TryCast(e.Control, ComboBox)
        If (cbo IsNot Nothing) Then
            RemoveHandler cbo.SelectedIndexChanged, AddressOf comboBox_SelectedIndexChanged

            AddHandler cbo.SelectedIndexChanged, AddressOf comboBox_SelectedIndexChanged
        End If
    End If

End Sub

Private Sub comboBox_SelectedIndexChanged(ByVal sender As Object, ByVal e As EventArgs)

    Dim combo As ComboBox = TryCast(sender, ComboBox)
    Dim rowIndex As Long = DataGridView1.CurrentRow.Index
    Dim valueType As Type = GetType(Long)

    If (combo.SelectedValue IsNot Nothing) Then
        Dim comboValueType As Type = combo.SelectedValue.GetType()
        Dim p As Boolean = valueType.Equals(comboValueType)

        If Not valueType.Equals(comboValueType) Then
            Exit Sub
        End If
    End If

    DataGridView1.Rows(rowIndex).Cells(2).Value = 'Some DB query to retrieve the value

End Sub

The first problem that I have is that when I open the list of the combobox and type I to select one item of the combobox that start with I. The combobox doesn't refresh to select this item and always goes back to the first item in the combobox, so what I do to make this work was change the value of the combobox on his own SelectedIndexChange like this:

Private Sub comboBox_SelectedIndexChanged(ByVal sender As Object, ByVal e As EventArgs)

    Dim combo As ComboBox = TryCast(sender, ComboBox)
    Dim rowIndex As Long = DataGridView1.CurrentRow.Index
    Dim valueType As Type = GetType(Long)

    If (combo.SelectedValue IsNot Nothing) Then
        Dim comboValueType As Type = combo.SelectedValue.GetType()
        Dim p As Boolean = valueType.Equals(comboValueType)

        If Not valueType.Equals(comboValueType) Then
            Exit Sub
        End If
    End If

    DataGridView1.Rows(rowIndex).Cells(1).Value = combo.SelectedValue
    DataGridView1.Rows(rowIndex).Cells(2).Value = 'Some DB query to retrieve the value
End Sub

The second problem is when I type another letter to select an item that starts with that letter and without pressing enter or clicking in the item that I changed to another DatagridViewComboboxCell the combobox that raises the SelectedIndexChanged event again which changes its value to the first item in the combobox.

Any idea why this happens?

Answer 1

You are quite close. This is what I did to the selectedIndexChanged to make it update.

I've noticed that the problem seems to lie in the line combo.SelectedValue. This value never change unless you leave the cell. What you need to use is combo.SelectedItem which changes everytime you change the combobox.

Try this instead:

Private Sub comboBox_SelectedIndexChanged(ByVal sender As Object, ByVal e As EventArgs)
Dim combo As ComboBox = TryCast(sender, ComboBox)
Dim test As Long
If (combo.SelectedItem IsNot Nothing) Then   
    If Not Long.TryParse(combo.SelectedItem, test) Then
            Exit Sub
    End If
End If
DataGridView2.CurrentCell.Value = combo.SelectedItem
DataGridView1.Rows(rowIndex).Cells(1).Value = combo.SelectedItem
DataGridView1.Rows(rowIndex).Cells(2).Value = 'Some DB query to retrieve the value

I changed the way you are checking if it is a Long. If it passes the Long.TryParse then it is a long. This code works for me to change the value of other Cells if this doesn't fix it, then I'm not sure what will. I also altered all SelectedValue to SelectedItem since SelectedValue always holds the last selected Value, and not the current.