ComboBox selection cleared in a tab control

Question

I am doing c# winform development.

I have a tabcontrol that consists several tabpages. Some of the tabpages are filled with usercontrol fully, some are just filled with combboxes/textboxes as such.

I set datasource for comboboxes and it loaded ok. But, when I pass the entire tabcontrol instance as a parameter to another form, in the new form, the combo box selections are cleared and set to first item selected.

Strangely enough, for comboboxes that was put in a usercontrol, the selections were not clear and shown correctly in the new form. Only those were put directly in tab page do not work.

Any suggestions or help will be appreciated.

Answer 1

bro. Fine? About the combobox problem, i have the same. I solve by this way: don't use DataSource

Before (with problem):

comboBox.DisplayMember = "NmConta";
comboBox.ValueMember = "CodConta";
comboBox.DataSource = dataTable;            

After (nothing problem):

comboBox.DisplayMember = "Value";
comboBox.ValueMember = "Key";
foreach (DataRow row in dataTable.Rows)
{
    comboBox.Items.Add(new KeyValuePair<int, string>(Convert.ToInt32(row["CodConta"]), Convert.ToString(row["NmConta"])));
}

Answer 2

After the implementation above, i need to write this methods for read and write comboBox.SelectedValue:

// Set ComboBox.SelectedValue
private void ComboBoxSelectedValue(ComboBox comboBox, object valueToSelect)
{
    for (int i = 0; i < comboBox.Items.Count; i++)
    {
        object item = comboBox.Items[i];
        object value = item.GetType().GetProperty("Key").GetValue(item, null);
        if (Convert.ToString(value) == Convert.ToString(valueToSelect))
        {
            comboBox.SelectedIndex = i;
            return;
        }
    }
    comboBox.SelectedIndex = -1;
}

// Get ComboBox.SelectedValue
private object ComboBoxSelectedValue(ComboBox comboBox)
{
    if (comboBox.SelectedIndex < 0) { return null; }
    object item = comboBox.Items[comboBox.SelectedIndex];
    return item.GetType().GetProperty("Key").GetValue(item, null);
}

// Get ComboBox.SelectedText
private object ComboBoxSelectedText(ComboBox comboBox)
{
    if (comboBox.SelectedIndex < 0) { return null; }
    object item = comboBox.Items[comboBox.SelectedIndex];
    return item.GetType().GetProperty("Value").GetValue(item, null);
}