C＃无法获取类型为已投入数据格式的DataSource

Question

我有一个带有tabpages的TabControl，每个tabpages都有一个datagridview，它在运行时生成并在运行时再次与数据源绑定。这是执行此操作的代码：

foreach (string cat in category)  //category is a list of categories I wish to make tabs for
{
    TabPage page = new TabPage(cat);
    DataGridView data = new DataGridView();
    data.Name = "Data";
    data.Location = new Point(1, 0);
    data.AllowUserToDeleteRows = false;
    data.ReadOnly = true;
    data.Anchor = AnchorStyles.Bottom | AnchorStyles.Left | AnchorStyles.Right | AnchorStyles.Top;
    data.MultiSelect = false;

    //here load data for the datagridview
    try
    {
         using (MySqlConnection connection = new MySqlConnection(Class1.connString))
         {
             string sql = "SELECT Code, `Problem Description` FROM problemcode WHERE Category = '" + cat + "' AND Type = 'Problem' ORDER BY `Problem Description`";

             connection.Open();
             using (MySqlCommand cmdSel = new MySqlCommand(sql, connection))
             {
                   DataTable dt = new DataTable();
                   MySqlDataAdapter da = new MySqlDataAdapter(cmdSel);
                   da.Fill(dt);
                   data.DataSource = dt;
             }
             connection.Close();
         }
   }
   catch (Exception ex)
   {
        MessageBox.Show("Unable to load problem data.\n\n" + ex.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Warning);
   }

   //here I add the datagridview to the tab
   page.Controls.Add(data);
   this.tabControl1.TabPages.Add(page);

   data.CellDoubleClick += new DataGridViewCellEventHandler(data_CellDoubleClick);
   data.CellEnter += new DataGridViewCellEventHandler(data_CellEnter);

}

为了便于讨论，我将从一个标签中讨论datagridview。我想在单击选项卡时访问此datagridview的数据源，但由于它是在运行时生成的，所以我这样做：

BindingSource bs = new BindingSource();
DataGridView selectedDtgv = new DataGridView();

if (tabControl1.SelectedTab.Controls.ContainsKey("Data")) //find datagridview named "Data"
{
    selectedDtgv = (DataGridView)tabControl1.SelectedTab.Controls["Data"];
    bs.DataSource = selectedDtgv.DataSource;
}

但是我的BindSource bs对象中没有数据。如果我做了像selectedDtgv.Rows.Count这样的东西，它给了我正确的行数，为什么它不给我DataSource？