[.NET 2.0+] Adding a ComboBox Column to a DataGridView

[jmcilhinney]

Nice work

But i have one problem and dont know how to solve it. I already have appplication with a lot of combos and textboxes on form (32 rows, in each row 5 combos and 5 texboxes and lot of code behind). Problem is that curent app is very slow on form load. With your sample i could make it a lot faster.

Already have gridview filled with some test data.

And the problem is:

When i click on combobox in use this code to display dropdown (to click only once to display dropdown).

When i click on item in dropdown the cell is filled with selected text. But CellValueChanged event is fired when i go out from cel in clicked on other cell. Now how i set that value is changed when i click on item in dropdown, or to catch this event?

I need this for enable or disable (ready only) next cell in gridview.

An one more thing.

I want to add one column in gridview like row number, starting with 0.

What you think you need, you don't need. First up, you don't need any code to make the combo boxes drop down with a single click. You simply set the EditMode property to EditOnEnter.

As for the cell value changing, whether it changes as soon as the user makes a selection or when they navigate away is irrelevant. To navigate to another cell they must navigate away from the current cell, so the CellValueChanged event will be raised and you can configure the other cells in the row regardless. Here's an update to the code from the first post in this thread:

Private Sub Form1_Load(ByVal sender As Object, _
                       ByVal e As EventArgs) Handles MyBase.Load
    Me.BindingSource2.DataSource = Me.GetParentTable()
    Me.Column1.DisplayMember = "ParentName"
    Me.Column1.ValueMember = "ParentID"
    Me.Column1.DataSource = Me.BindingSource2

    Me.BindingSource1.DataSource = Me.GetChildTable()
    Me.DataGridView1.DataSource = Me.BindingSource1
End Sub

Private Function GetParentTable() As DataTable
    Dim table As New DataTable

    With table.Columns
        .Add("ParentID", GetType(Integer))
        .Add("ParentName", GetType(String))
    End With

    With table.Rows
        .Add(1, "Parent 1")
        .Add(2, "Parent 2")
        .Add(3, "Parent 3")
    End With

    Return table
End Function

Private Function GetChildTable() As DataTable
    Dim table As New DataTable

    With table.Columns
        .Add("ChildID", GetType(Integer))
        .Add("ParentID", GetType(Integer))
        .Add("ChildName", GetType(String))
    End With

    With table.Rows
        .Add(1, 3, "Child 1")
        .Add(2, 2, "Child 2")
        .Add(3, 1, "Child 3")
    End With

    Return table
End Function

Private Sub DataGridView1_CellValueChanged(ByVal sender As Object, _
                                           ByVal e As DataGridViewCellEventArgs) Handles DataGridView1.CellValueChanged
    Dim row = e.RowIndex
    Dim column = e.ColumnIndex

    If column = 1 Then
        If CInt(Me.DataGridView1(column, row).Value) = 2 Then
            Me.DataGridView1(0, row).ReadOnly = True
            Me.DataGridView1(2, row).ReadOnly = True
        Else
            Me.DataGridView1(0, row).ReadOnly = False
            Me.DataGridView1(2, row).ReadOnly = False
        End If
    End If
End Sub

Also, set the EditMode of the grid in the designer. Now, try running that code and editing the values in the first column. You'll find that the combo boxes drop down on the first click, assuming that you click the drop-down arrow and not the text area. Also note that, if you select 'Parent 2', the rest of the cells in the row become read-only while, if you select a different parent, the other cells are editable.