Question

我需要在运行时创建许多下拉列表，并为每个选择一个不同的项目。为了避免连续访问数据库，我创建了一个下拉列表，将其复制到克隆的下拉列表中。奇怪的是，所有创建的下拉列表都选择了上一个下拉列表中的项目，我不明白为什么！我必须插入所选项目的清洗[“ DlistClone.ClearSelection（）”]，因为否则代码会出错。谁能帮我？谢谢

   Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click
    Dim MyRow As New TableRow
    Dim MyCell As New TableCell

    Dim DList As DropDownList
    Dim DlistClone As DropDownList
    DList = New DropDownList
    DList.Items.Add("1")
    DList.Items.Add("2")
    DList.Items.Add("3")

    MyRow = New TableRow
    MyCell = New TableCell
    DlistClone = New DropDownList
    ClonaDList(DList, DlistClone)
    DlistClone.ClearSelection()
    DlistClone.Items.FindByText("3").Selected = True
    MyCell.Controls.Add(DlistClone)
    MyRow.Cells.Add(MyCell)

    Table1.Rows.Add(MyRow)

    MyRow = New TableRow
    MyCell = New TableCell
    DlistClone = New DropDownList
    ClonaDList(DList, DlistClone)
    DlistClone.ClearSelection()
    DlistClone.Items.FindByText("2").Selected = True
    MyCell.Controls.Add(DlistClone)
    MyRow.Cells.Add(MyCell)

    Table1.Rows.Add(MyRow)
End Sub

Sub ClonaDList(ByVal Origine As DropDownList, ByVal Destinazione As DropDownList)
    Dim I As Integer
    Dim EleList As ListItem

    For I = 0 To Origine.Items.Count - 1
        EleList = Origine.Items(I)
        Destinazione.Items.Add(EleList)
    Next I
End Sub

Answer 1

好的，我自己弄的！当我这样做

EleList = Origin.Items（I）
Destination.Items.Add（EleList）

我在源Dropdownlist和目标Dropdownlist之间创建了意外绑定。要中断绑定，我必须在两个控件之间建立一个桥梁，在这种情况下，我将通过两个连续的步骤设置两个属性来使用Listitem对象

Sub ClonaDList(ByRef Origine As DropDownList, ByRef Destinazione As DropDownList)
    Dim I As Integer
    Dim EleList As ListItem

    For I = 0 To Origine.Items.Count - 1
        EleList = New ListItem
        EleList.Text = Origine.Items(I).Text
        EleList.Value = Origine.Items(I).Value
        Destinazione.Items.Add(EleList)
    Next I
End Sub

我说的对吗？

在运行时创建的不同DropDownLists不允许选择其他项？

1 个答案: