Problem setting DataSource for dynamically created ComboBox

[MichaelNattfalk]

Hi.

I'm having kind of a weird problem which I hope someone can help me with.

I have a form on which I have a ComboBox created at design-time.
When I run the application I dynamically create x more ComboBoxes
beneth the one created at design-time.

At run-time I set the DataSource, DataMember and ValueMember for all the ComboBoxes,
both the one created at design-time the the ones created at run-time.
After this is done I set the SelectedValue property to a value retrived
from another sql-query.

Now my problem occures. Setting the SelectedValue property works for the
control created at design-time but not for the controls created at run-time.

When I debug the code that sets the DataSources I see that the ComboBox,
created at design-time, has items in the items-collection so therefore I
can set the SelectedValue accordingly.
But the controls created at run-time doesn't have any items in the the collection.
However, if I continue to run the application and look at the run-time-created
comboboxes on the form, all the correct items is in the list.
But I can't set a selected item in code directly after setting the datasource?!?!

Does dynamically created controls need some refreshing/updating before the data is
available in the list?

Here is an excerpt from the code creating the controls and setting the properties.

    ComboBox cbNew = new ComboBox();
    cbNew.Name = "cbLine" + (i+1);
    cbNew.Size = cbLine1.Size;
    cbNew.Location = new Point(cbLine1.Location.X, cbLine1.Location.Y + 26*i);
    cbNew.Enabled = false;
    cbNew.DropDownStyle = ComboBoxStyle.DropDownList;
    cbNew.DataSource = DBLayer.GetTeams(lineName).Tables[0];
    cbNew.DisplayMember = "teamdesc";
    cbNew.ValueMember = "id";
    Console.WriteLine("ComboBox {0}, itemcount={1}", cbNew.Name, cbNew.Items.Count);
        // The output displays itemcount = 0 for run-time created controls
        // and >0 for controls created at design-time
    gbLines.Controls.Add(cbNew);

cbLine1 is the ComboBox created at design-time.

Here is the code for setting the SelectedValue property.

        private void InitItemTeamStationData()
        {
            OleDbDataReader reader = DBLayer.GetITSData(itemID);
            if(reader == null)
                return;

            while (reader.Read())
            {
                for (int i = 1; i <= numberOfLines; i++)
                {
                    CheckBox chkbox = (CheckBox)gbLines.Controls["chkLine" + i];
                    if (chkbox != null)
                    {
                        int tagValue = 0;
                        if (Int32.TryParse(chkbox.Tag.ToString(), out tagValue) == true)
                        {
                            if (tagValue == reader.GetInt32(reader.GetOrdinal("line")))
                            {
                                chkbox.Checked = true;

                                ComboBox team = (ComboBox)gbLines.Controls["cbLine" + i];
                                // The following works for design-time created controls, but not run-time
                                team.SelectedValue = reader.GetInt32(reader.GetOrdinal("team"));

                                ComboBox station = (ComboBox)gbLines.Controls["cbStation" + i];
                                // The following works for design-time created controls, but not run-time
                                station.SelectedValue = reader.GetInt32(reader.GetOrdinal("station"));

                                break;
                            }
                        }
                    }
                }
            }
        }

What am I missing?
Hope someone can help me with this.

Best regards,
Michael

[MichaelNattfalk]

I found the problem.

I changed the following code from

    ComboBox cbNew = new ComboBox();
    cbNew.Name = "cbLine" + (i+1);
    cbNew.Size = cbLine1.Size;
    cbNew.Location = new Point(cbLine1.Location.X, cbLine1.Location.Y + 26*i);
    cbNew.Enabled = false;
    cbNew.DropDownStyle = ComboBoxStyle.DropDownList;
    cbNew.DataSource = DBLayer.GetTeams(lineName).Tables[0];
    cbNew.DisplayMember = "teamdesc";
    cbNew.ValueMember = "id";
    Console.WriteLine("ComboBox {0}, itemcount={1}", cbNew.Name, cbNew.Items.Count);
        // The output displays itemcount = 0 for run-time created controls
        // and >0 for controls created at design-time
    gbLines.Controls.Add(cbNew);

to

    ComboBox cbNew = new ComboBox();
    cbNew.Name = "cbLine" + (i+1);
    cbNew.Size = cbLine1.Size;
    cbNew.Location = new Point(cbLine1.Location.X, cbLine1.Location.Y + 26*i);
    cbNew.Enabled = false;
    cbNew.DropDownStyle = ComboBoxStyle.DropDownList;
    Console.WriteLine("ComboBox {0}, itemcount={1}", cbNew.Name, cbNew.Items.Count);
        // The output displays itemcount = 0 for run-time created controls
        // and >0 for controls created at design-time
    gbLines.Controls.Add(cbNew);
    cbNew.DataSource = DBLayer.GetTeams(lineName).Tables[0];
    cbNew.DisplayMember = "teamdesc";
    cbNew.ValueMember = "id";

The DataSource, DisplayMember and ValueMember property must be set after the control has been added to its container.

Works fine now.

Best regards,
Michael