Question

我有一个面板，我可以添加一组组合框和文本框。我想从我的数据库中添加项目到动态添加的组合框。如何添加项目以动态添加组合框？

这是我通过点击按钮动态添加组合框的代码。

    Dim number As Integer = 2
  Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
    Dim itemCombobox As New ComboBox
    itemCombobox.Name = "itemCombobox" + number.ToString
    itemCombobox.Location = New Point(25, number * 29)
    itemCombobox.Size = New Point(113, 23)
    itemCombobox.DropDownStyle = ComboBoxStyle.DropDownList

    Dim qtyTxtbox As New MaskedTextBox
    qtyTxtbox.Name = "qtyTxtbox" + number.ToString
    qtyTxtbox.Location = New Point(172, number * 29)
    qtyTxtbox.Size = New Point(37, 20)

    Dim specsBtn As New ComboBox
    specsBtn.Name = "specsBtn" + number.ToString
    specsBtn.Location = New Point(236, number * 29)
    specsBtn.Size = New Point(113, 23)
    specsBtn.DropDownStyle = ComboBoxStyle.DropDownList

    Dim bmCombobox As New ComboBox
    bmCombobox.Name = "bmCombobox" + number.ToString
    bmCombobox.Location = New Point(385, number * 29)
    bmCombobox.Size = New Point(113, 23)
    bmCombobox.DropDownStyle = ComboBoxStyle.DropDownList

    Panel8.Controls.Add(itemCombobox)
    Panel8.Controls.Add(qtyTxtbox)
    Panel8.Controls.Add(specsBtn)
    Panel8.Controls.Add(bmCombobox)
    number = number + 1

End Sub

这是我将项目添加到itemcombobox

的功能

Private Sub load_item1()
    Dim conn As New MySqlConnection
    conn.ConnectionString = "server=127.0.0.1;  username=root; password=p@ssw0rd; database= atos_db"
    Dim reader As MySqlDataReader
    Try
        conn.Open()
        Dim query As String
        query = "select * from atos_db.item_tbl"
        comm = New MySqlCommand(query, conn)
        reader = comm.ExecuteReader
        While reader.Read
            Dim sItem = reader.GetString("item")
            itemCombobox1.Items.Add(sItem)
        End While
        conn.Close()
    Catch ex As MySqlException
        MessageBox.Show(ex.Message)
    Finally
        conn.Dispose()
    End Try
End Sub

如何获取每个动态添加的控件的值？

Answer 1

您的变量“itemCombobox”在方法“Button1_Click”中声明，因此无法在您的方法“load_item1”中使用它。要做到这一点，你必须在你的classe声明你的变量为全局变量：

      Dim itemCombobox As New ComboBox
     Dim number As Integer = 2
      Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        itemCombobox.Name = "itemCombobox" + number.ToString
        itemCombobox.Location = New Point(25, number * 29)
        itemCombobox.Size = New Point(113, 23)
        itemCombobox.DropDownStyle = ComboBoxStyle.DropDownList

        Dim qtyTxtbox As New MaskedTextBox
        qtyTxtbox.Name = "qtyTxtbox" + number.ToString
        qtyTxtbox.Location = New Point(172, number * 29)
        qtyTxtbox.Size = New Point(37, 20)

        Dim specsBtn As New ComboBox
        specsBtn.Name = "specsBtn" + number.ToString
        specsBtn.Location = New Point(236, number * 29)
        specsBtn.Size = New Point(113, 23)
        specsBtn.DropDownStyle = ComboBoxStyle.DropDownList

        Dim bmCombobox As New ComboBox
        bmCombobox.Name = "bmCombobox" + number.ToString
        bmCombobox.Location = New Point(385, number * 29)
        bmCombobox.Size = New Point(113, 23)
        bmCombobox.DropDownStyle = ComboBoxStyle.DropDownList

        Panel8.Controls.Add(itemCombobox)
        Panel8.Controls.Add(qtyTxtbox)
        Panel8.Controls.Add(specsBtn)
        Panel8.Controls.Add(bmCombobox)
        number = number + 1

       Dim theButton As Button
       theButton = New Button
       theButton.Location = location
       theButton.Text = label
       AddHandler theButton.Click, AddressOf Me.btn_clicked

    End Sub

并在方法load_item1()中使用此变量：

Private Sub load_item1()
    Dim conn As New MySqlConnection
    conn.ConnectionString = "server=127.0.0.1;  username=root; password=p@ssw0rd; database= atos_db"
    Dim reader As MySqlDataReader
    Try
        conn.Open()
        Dim query As String
        query = "select * from atos_db.item_tbl"
        comm = New MySqlCommand(query, conn)
        reader = comm.ExecuteReader
        While reader.Read
            Dim sItem = reader.GetString("item")
            itemCombobox.Items.Add(sItem)
        End While
        conn.Close()
    Catch ex As MySqlException
        MessageBox.Show(ex.Message)
    Finally
        conn.Dispose()
    End Try
End Sub

Private Sub btn_clicked(ByVal sender As System.Object, ByVal e As System.EventArgs)
    Dim selectedBtn As Button = sender
    MsgBox("you have clicked button " & selectedBtn.Name)
End Sub

将Combobox项添加到动态添加的控件

1 个答案: