Why can't I add Items to a ComboBox that is accessed using this.tableLayoutPanel1.GetControlFromPosition(i, j)

Question

I have created ComboBox Controls when my Form Loads and I want to add Items to them later when the user makes specific selections but, I cannot use Items.Add because the compiler reports a Compiler Error CS1061 'Control' does not contain a definition for 'Items'

tableLayoutPanel1 = tblRinks

Code that creates the ComboBox:

for (var r = 2; r <= Globals.tSheets; r++)

{

tblRinks.RowStyles.Add(new RowStyle(SizeType.Percent, 100F));

tblRinks.RowCount++;

tblRinks.ColumnStyles.Add(new ColumnStyle(SizeType.Absolute, 95F));

tblRinks.Controls.Add(new Label() { Text = "Sheet " + x, Name = "lblSheet" + r, Font = new Font("Microsoft Sans Serif, 9pt, style=Bold center", 9), TextAlign = ContentAlignment.MiddleCenter }, 0, r);

//

tblRinks.ColumnStyles.Add(new ColumnStyle(SizeType.Absolute, 162F));

tblRinks.Controls.Add(new ComboBox() { Name = "cboRink" + r + "A", Font = new Font("Microsoft Sans Serif, 9pt, style=Bold, align=center", 9) }, 1, r);

//

tblRinks.ColumnStyles.Add(new ColumnStyle(SizeType.Absolute, 26F));

tblRinks.Controls.Add(new Label() { Text = "VS", Font = new Font("Microsoft Sans Serif, 9pt, style=Bold, align=center", 9), TextAlign = ContentAlignment.MiddleCenter }, 2, r);

//

tblRinks.ColumnStyles.Add(new ColumnStyle(SizeType.Absolute, 162F));

tblRinks.Controls.Add(new ComboBox() { Name = "cboRink" + r + "B", Font = new Font("Microsoft Sans Serif, 9pt, style=Bold, align=center", 9) }, 3, r);

x++;

}

Code used to access the ComboBoxes after user selects from another ComboBox:

for (int r = 0; r < tblRinks.Controls.Count; r++)

{

Control cbo = tblRinks.Controls[r];

if (cbo is ComboBox && cbo.Name == "cboRink2B")

{

  foreach (string team in Globals.rList)

  {

    string tname = team;

    if (tname != ((Control)sender).Text && tname != cboRink1A.Text)

    {

      mList.Add(tname);

      tblRinks.Controls[r].Enabled = true;

      int idx = tblRinks.Controls[r].Handle.ToInt32();

      //MessageBox.Show(idx.ToString());

      //tblRinks.Controls[r].items.Add(tname);

    }

  }

  cbo.BackColor = Color.LightGoldenrodYellow;

  ((Control)sender).BackColor = Color.White;

  return;

}

}

Answer 1

Hi @Michael Bahr , Welcome to Microsoft Q&A,

You treat the ComboBox control as a more general Control class, which does not have an Items property. This results in compiler error CS1061.

In order to correctly add items to a ComboBox, you need to explicitly cast the Control type to the ComboBox type before you can access its Items property.

for (int r = 0; r < tblRinks.Controls.Count; r++)
{
    Control control = tblRinks.Controls[r];
    if (control is ComboBox comboBox && comboBox.Name == "cboRink2B")
    {
        foreach (string team in Globals.rList)
        {
            string tname = team;

            if (tname != ((Control)sender).Text && tname != cboRink1A.Text)
            {
                comboBox.Items.Add(tname);
            }
        }

        comboBox.BackColor = Color.LightGoldenrodYellow;
        ((Control)sender).BackColor = Color.White;

        return;
    }
}

Best Regards,

Jiale

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