Question

我正在动态创建一个表，在每行中放置一个动态创建的radiobuttonlist。

然后，我想在单击提交按钮时在页面上显示结果。

我收到一条错误消息，指出

'question1'未声明

为什么会发生这种情况？我在下面列出了所有代码。

代码背后：

Sub Page_Load(ByVal Sender as Object, ByVal E as EventArgs)

    For i As Integer = 1 To 3
        Dim TableRow As New TableRow()
        Dim TableRowCell_1 As New TableCell()
        TableRowCell_1.Text = i
        Dim TableRowCell_2 As New TableCell()

        TableRow.Cells.Add(TableRowCell_1)
        TableRow.Cells.Add(TableRowCell_2)
        QuestionnaireTable.Rows.Add(TableRow)

        Dim question As New RadioButtonList
        question.ID = "question" & i
        question.RepeatColumns = "2"
        question.Items.Insert(0, new listitem("", "1"))
        question.Items.Insert(1, new listitem("", "2"))
        TableRowCell_3.Controls.Add(question)
    Next

End Sub

Sub btnSendFeedback_Click(sender as Object, e as EventArgs)
    Dim question1 As RadioButtonList = DirectCast(Page.FindControl("question1"), RadioButtonList)
    Dim question2 As RadioButtonList = DirectCast(Page.FindControl("question2"), RadioButtonList)
    Dim question3 As RadioButtonList = DirectCast(Page.FindControl("question3"), RadioButtonList)
    Response.write(question1.SelectedValue & " - " & question2.SelectedValue & " - " & question3.SelectedValue)
End Sub

身体：

<asp:Table runat="server" ID="QuestionnaireTable" />

<asp:Button OnClick="btnSendFeedback_Click" runat="server" Text="Submit..." ID="submitbutton" />

Answer 1

我可以看到你没有在任何地方声明：）

由于“问题1”是您的ID，您必须使用FindControl找到它。

Page.FindControl(myId)

如果您只有3个项目，可以在当前对象中定义它以便更好地使用。

private question1 as RadioButtonList
private question2 as RadioButtonList

Sub Page_Load(ByVal Sender as Object, ByVal E as EventArgs)
     me.question1 = new RadioButtonList
End Sub

Sub btnSendFeedback_Click(sender as Object, e as EventArgs)
        dim value = me.question1.selectedValue
End Sub

或者你可以做这样的事情

private rbls as new List(of RadioButtonList)

Sub Page_Load(ByVal Sender as Object, ByVal E as EventArgs)
     dim list1 as new RadioButtonList
     list.items.add...
     rbls.add(list)
End Sub

Sub btnSendFeedback_Click(sender as Object, e as EventArgs)
        For Each _item in Me.rbls
              Response.write(_item.SelectedValue)
        End For
End Sub

Answer 2

当您在标记中声明控件时，Visual Studio和ASP.NET会使它成为可以在代码隐藏中访问该控件的。

当你像这样动态地声明一个控件时，你必须从代码隐藏中进行访问。

有多种方法可以做到这一点，可能最简单的方法是：

Dim question1 As RadioButtonList = DirectCast(Page.FindControl("question1"), RadioButtonList)

动态创建的radiobuttonlist“未声明”

2 个答案: