[RESOLVED] Add a combobox column to DGV

[patel45]

Here is my code

       Dim connStr As String = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=F:\Documenti\Visual Studio 2017\Projects\Rubrica.mdb"

        Dim Adapter1 As OleDbDataAdapter
        Dim sSQL As String = "SELECT VOTO FROM VOTI"
        Dim Dt1 As DataTable = New DataTable
        Dim Cmd As New OleDbCommand(sSQL, Conn)
        Adapter1 = New OleDbDataAdapter(Cmd)
        Adapter1.Fill(Dt1)
        DataGridView2.DataSource = Dt1
        Dim column As New DataGridViewComboBoxColumn

        DataGridView2.Columns.Add(column)
        column.DataSource = Dt1

My output is shown on attached image, how can I fix it ?

[.paul.]

Generally, you wouldn't be binding the same datasource both for the dgv and the column...

column.DisplayMember = "field name"

[patel45]

it's just to show that with the same datatable I can't populate the combo column.
Thank You Paul, your suggestion works, why displaymember is needed?

[.paul.]

A datatable is a collection of fields and rows. If you don't specify which field to use, it attempts to use the whole row, which is System.Data.DataRowView

[patel45]

My data table has only one field but I understand now, thanks.

[jmcilhinney]

You really need to set the DisplayMember and the ValueMember. Here's how it works. You bind data to your grid as normal so each cell in that column has a Value from that data source. For each cell, the Value is used as a lookup in the column or property of the column data source specified in the ValueMember. That selectes the row from the column data source and the value in the column or property of the column data source specified in the DisplayMember is displayed in the cell. When you edit a cell, a ComboBox control is created and embedded in the cell. The Value of the cell is assigned to the SelectedValue of the editing control and the corresponding item is selected and displayed. When you select an item and end the editing session, the SelectedValue of the ComboBox control is assigned back to the Value of the cell.

[patel45]

Thanks jmc for the explanation