从 vb.net 中以编程方式创建的组合框中选择值

Question

我在一个面板中创建了一系列组合框，我可以毫不费力地使用数据库中的正确值填充每个组合框，但我无法提取（放入变量）我在何时选择的值单击任何组合框。我尝试了几件事无济于事。我在另一个使用列表的站点上查看了某人提出的解决方案，但这要么不适用于我的问题，要么我不理解它。任何帮助，将不胜感激。我已经为此苦苦挣扎了好几个星期。非常感谢！

这是我的代码的相关部分：

Private Sub llenaPanelKeywords()

      Try

            combokywrd = New System.Windows.Forms.ComboBox
            combokywrd.Left = kywrdLabel.Left + kywrdLabel.Width + 1
            combokywrd.Top = 10 + SaltoDeFilaKeywords * 30 
            combokywrd.Width = 81
            combokywrd.Height = 25
            combokywrd.Font = New System.Drawing.Font("Microsoft Sans Serif", 10.0!, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, CType(0, Byte))

            PanelKywrds.Controls.Add(combokywrd)

            combokywrd.Name = kwDataTable.Rows(kwRowPosition)("IdKeyword").ToString()

            'the combo gets populated only upon clicking on it:
            AddHandler combokywrd.Click, AddressOf combokywrd_click

        SaltoDeFilaKeywords = SaltoDeFilaKeywords + 1

    Catch ex As Exception
        MessageBox.Show("falla en llenar panel keywords " & ex.Message)
    End Try

End Sub

Private Sub combokywrd_click(sender As Object, e As EventArgs) Handles combokywrd.Click

    Try

        Dim combokywrd As ComboBox = CType(sender, ComboBox)

        idKeywordSelect = combokywrd.Name.ToString()

                    combokywrd.DataSource = Nothing 'por alguna razón antes de poner esto, fallaba al llenar uno de los combos, pero no los demás (largo total)

        combokywrd.Items.Clear()

        Dim stringSQLValorKywrd = "SELECT DISTINCT valorKeyword FROM [TOOLTOWERDbase].[dbo].[articuloKeyword] WHERE idKeyword = " & idKeywordSelect 


        Dim cmd As New SqlCommand(stringSQLValorKywrd, con)
        cmd.CommandType = CommandType.Text
        Dim sda As New SqlDataAdapter(cmd)
        Dim dtVK As New DataTable()
        sda.Fill(dtVK)

        combokywrd.DataSource = dtVK
        combokywrd.DisplayMember = "valorkeyword"
        lstCombos.Add(combokywrd)


        combokywrd.Tag = combokywrd.Name

        AddHandler (combokywrd.SelectedValueChanged), AddressOf combokywrd_SelectedValueChanged 

    Catch ex As Exception
        MessageBox.Show("carga valoresKeyword falló " & ex.Message)
    End Try

End Sub


Private Sub combokywrd_SelectedValueChanged(sender As Object, e As EventArgs) Handles combokywrd.SelectedValueChanged

    'I cannot go beyond populating the comboboxes:
    'I have tried with selectedindexchanged as well


    MessageBox.Show(combokywrd.SelectedText.ToString()) 'shows blank

    Dim cb As ComboBox = DirectCast(sender, ComboBox)

    MsgBox(cb.SelectedValue.ToString()) 'shows System.Data.DataRowView

    MsgBox("combobox’s tag: " & cb.Tag.ToString()) 'it shows the correct tag

    Dim tempString = combokywrd.Items(combokywrd.SelectedValue).ToString  'value of ‘0’ is not valid for index

End Sub

Answer 1

MsgBox(cb.SelectedValue.ToString()) 'shows System.Data.DataRowView

你得到了值，但你没有在组合框中放一个字符串，而是放了一整行。 （因为你绑定到一个表，而不是一个列表。）尝试 cb.SelectedValue[0].ToString()，如果这不起作用，在行上放一个断点，转到立即窗口（ctrl+g） ，键入 cb.SelectedValue。看看在第二个“.”之后会出现什么选项，你会发现那里有一些东西可以让你得到行的想要的字段而不是整行。