Asp.net 动态创建的radiobuttonlist

有一个母版页。内容页有一个包含请求变量的超链接列表。您单击其中一个链接可转到包含radiobuttonlist（可能）的页面

第一个问题：当我进入新页面时，我使用其中一个变量来确定是否向页面上的占位符添加radiobuttonlist。我尝试在页面加载中执行此操作，但无法选择值。当我在preInit中玩的时候，当页面第一次出现时，我无法访问页面的控件。（对象引用未设置为对象的实例。）我认为它与母版页和页面内容有关？控件直到稍后才实例化？（顺便说一下，使用vb）

第二个问题：假设我让它工作，一旦我按下一个按钮，我仍然可以访问传递的请求变量来确定radiobuttonlist中的所选项目吗

    Protected Sub Page_PreInit(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.PreInit
    'get sessions for concurrent 

    Dim Master As New MasterPage
    Master = Me.Master

    Dim myContent As ContentPlaceHolder = CType(Page.Master.FindControl("ContentPlaceHolder1"), ContentPlaceHolder)
    If Request("str") = "1" Then
        Dim myList As dsSql = New dsSql()   ''''instantiate the function to get dataset
        Dim ds As New Data.DataSet

        ds = myList.dsConSessionTimes(Request("eid"))
        If ds.Tables("conSessionTimes").Rows.Count > 0 Then
            Dim conY As Integer = 1

            CType(myContent.FindControl("lblSidCount"), Label).Text = ds.Tables("conSessionTimes").Rows.Count.ToString

很抱歉这么需要，但也许有人能告诉我一个例子页面？也许看到它会有助于理解

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谢谢….JB

如果您有一个内容占位符，您可以将单选按钮列表控件添加到其中吗

在母版页上：

<asp:ContentPlaceHolder id="ContentPlaceHolderForRadioButtonList" runat="server">       
</asp:ContentPlaceHolder>

希望你能在这里找到一些有用的东西

<a href="RadioButtonList.aspx?ref=first" >Link 1</a>
<a href="RadioButtonList.aspx?ref=second" >Link 2</a><br />
<a href="RadioButtonList.aspx?ref=third" >Link 3</a><br />
<a href="RadioButtonList.aspx?ref=forth" >Link 4</a><br />
<a href="RadioButtonList.aspx?ref=fifth" >Link 5</a><br />
<a href="RadioButtonList.aspx?ref=sixth" >Link 6</a>

<asp:Content ID="Content3" ContentPlaceHolderID="ContentPlaceHolderForRadioButtonList" Runat="Server">
<!-- radio button list to be dynamically populated-->
    <asp:RadioButtonList ID="RadioButtonList1" runat="server">
    </asp:RadioButtonList>
</asp:Content>

 Partial Class RadioButtonList
    Inherits System.Web.UI.Page
    Private selection As String = ""

    Protected Sub Page_Init(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Init
        selection = IIf(Request.QueryString("ref") IsNot Nothing, Request.QueryString("ref"), "")
        If selection = "first" Then
            RadioButtonList1.Items.Add(New ListItem("first", "1"))
            RadioButtonList1.Items.Add(New ListItem("third", "3"))
            RadioButtonList1.Items.Add(New ListItem("fifth", "5"))
        ElseIf selection = "second" Then
            RadioButtonList1.Items.Add(New ListItem("second", "2"))
            RadioButtonList1.Items.Add(New ListItem("forth", "4"))
            RadioButtonList1.Items.Add(New ListItem("sixth", "6"))
        Else
            RadioButtonList1.Items.Add(New ListItem("first", "1"))
            RadioButtonList1.Items.Add(New ListItem("second", "2"))
            RadioButtonList1.Items.Add(New ListItem("third", "3"))
            RadioButtonList1.Items.Add(New ListItem("forth", "4"))
            RadioButtonList1.Items.Add(New ListItem("fifth", "5"))
            RadioButtonList1.Items.Add(New ListItem("sixth", "6"))
        End If

        'set the selected radio button
        For i As Integer = 0 To RadioButtonList1.Items.Count - 1
            If RadioButtonList1.Items(i).Text = selection Then
                RadioButtonList1.Items(i).Selected = True
                Exit For
            End If
        Next

    End Sub

End Class