设置选定索引时，C＃WinForms组合框不显示文本

Question

我对winforms组合框感到奇怪。

注意：这不是数据绑定 - 我从数据表中填充所有控件。

我将一个帐号列表添加到组合框中，然后在网格中显示一组记录在组合框文本值上的记录。

我可以添加帐号，在帐号之间切换，一切正常。

如果我从框中删除了一个帐号，我会从数据库中删除帐号和所有相关记录。这很好。

然后，我从accounts表中的剩余值重新填充组合框，并将SelectedIndex设置为0，以便将其设置为列表中的第一个帐号。

if(cboAccountNumbers.Items.Count > 0)
    {
        cboIBAccountNumbers.SelectedIndex = 0;
    }

然后我调用db来获取在combobox.Text值上键入的记录 - 这是有效的 - 有一个文本值，它是正确的，并返回数据。

DataTable dt = new DataTable();
dt = DataUtils.GetRowsByAccountNumber(cboAccountNumbers.Text);

但是，当表单重新获得焦点时，组合框文本为空白。

如果单击下拉列表，则会显示正确的项目 - 但是，与项目索引0关联的文本不会显示为组合框文本值。

有什么建议？

private void cboAccountNumbers_KeyDown(object sender, KeyEventArgs e)
    {
        DeleteAccountNumber(sender, e);

    }

private void DeleteAccountNumber(object sender, KeyEventArgs e)
    {
        if (e.KeyCode == Keys.Delete)
        {
            ComboBox cbo = (ComboBox)sender;

            DialogResult result = MessageBox.Show("Are you sure you want to delete this Account?\n\n" +
                                              "All strategies related to the account will be deleted as well.",
                                              "xxx",
                                              MessageBoxButtons.YesNoCancel,
                                              MessageBoxIcon.Hand);
            if (result == DialogResult.Yes)
            {
                using (PgSQLDb db = new PgSQLDb())
                {
                    // two things to do - delete intersection table values between 
                    // ib_account_numbers and strategies i.e. ib_account_numbers_vs_strategies
                    // then delete the account number itself

                    // 1. delete account_numbers_vs_strategies
                    db.Delete("account_numbers_vs_strategies", " account_number_id = (select id from account_numbers where acc_number ='" + cbo.Text + "')");

                    // 2. delete account_numbers record
                    db.Delete("account_numbers", "acc_number = '" + cbo.Text + "'");
                }

                GetAccounts(string.Empty);
            }
        }
    }

private void GetAccounts(string account)
    {

        DataTable dt = new DataTable();

        dt = DataUtils.GetAccountNumbersTable();

        string selectedItem = string.Empty;

        cboAccountNumbers.Items.Clear();

        foreach (DataRow row in dt.Rows)
        {
            cboAccountNumbers.Items.Add(row["acc_number"].ToString());
            if (Convert.ToBoolean(row["is_default"]))
            {
                selectedItem = row["acc_number"].ToString();
            }
        }

        // if an AccountNumber is passed in, use that (typically when a 
        // new account is created)
        // else use the default 
        // else use first item in list.
        if (!string.IsNullOrEmpty(account))
        {
            cboAccountNumbers.SelectedItem = account;
        }
        else if (!string.IsNullOrEmpty(selectedItem))
        {
            cboIBAccountNumbers.SelectedItem = selectedItem;
        }
        else
        {
            if(cboAccountNumbers.Items.Count > 0)
            {
                cboAccountNumbers.SelectedIndex = 0;
            }
        }            

        GetStrategies();
    }


private void GetStrategies()
    {
            DataTable dt = new DataTable();

            string selectedItem = cboAccountNumbers.Text;

            dt = DataUtils.GetRowsByAccountNumber(selectedItem);

            gvwMain.Rows.Clear();
            strategies.Clear(); // list of Strategy objects

            foreach (DataRow row in dt.Rows)
            {
                Strategy cd = new Strategy(Convert.ToInt16(row["strategies_id"]),
                                            row["name"].ToString(),
                                            Convert.ToBoolean(row["active"]),
                                            Convert.ToDecimal(row["percentage_of_portfolio"]),
                                            Convert.ToInt16(row["margin"])
                                            );
                strategies.Add(cd);
            }

            gvwMain.AutoGenerateColumns = false;
            BindingList<Strategy> bindingList = new BindingList<Strategy>(strategies);
            BindingSource source = new BindingSource(bindingList, null);
            gvwMain.DataSource = source;
            gvwMain.Refresh();
            FormatGrid();
        }
    }