Winform Set ComboBox占位符

Question

我有以下填充的ComboBox控件，如下所示

DataTable dt2 = InfoPCMS.db.executeSelectQuery("select * from Customer");

txtCustomer.DataSource = dt2;
txtCustomer.ValueMember = "Id";
txtCustomer.DisplayMember = "CustomerName";

如何設置占位符，說“選擇客戶”

Answer 1

這不能解決您的問題，但可以解決您的問題。 我認為有一種更好的方法可以完成這項工作，但這可行：

DataTable dt2 = InfoPCMS.db.executeSelectQuery("select * from Customer");

foreach (DataRow row in dt2.Rows)
{
    ComboboxItem newItem = newComboboxItem(row["id"], row["CustomerName"]);
    txtCustomer.Items.Add(newItem);
}
txtCustomer.Items.Insert(0,"Select a customer");
txtCustomer.SelectedIndex = 0;

public class ComboboxItem
{
    public string Text { get; set; }
    public object Value { get; set; }

    public ComboboxItem(object val, string txt)
    {
        this.Value = val;
         this.Text = txt;
    }
    public override string ToString()
    {
        return Text;
    }
}