无法将HiddenField转换为I.Convertible

Question

我有两个DataLists，其中一个嵌套在另一个中。我有一条线路(Dim QID....)这总是给我带来问题，不管我能在网上找到什么代码组合。我只想让Hidden Field显示为一个整数，这样If语句就可以工作了。

Dim dl2 As DataList = CType(e.Item.FindControl("DataList2"), DataList)
        Dim QID As Integer = Convert.ToInt32(e.Item.FindControl("HiddenField2"))
        If QID = 33 Then
                Dim lbl As Label = dl2.FindControl("Label3")
                For Each i As ListItem In dl2.Items
                    If lbl.Text = "Self Directed" Or lbl.Text = "Systems" Then
                        lbl.Visible = False
                    End If
                Next
        End If

<asp:DataList ID="DataList1" runat="server" DataSourceID="SqlDataSource1" 
 Width="100%" CellPadding="4" ForeColor="#333333">
<ItemTemplate>
<asp:HiddenField ID="HiddenField2" runat="server" 
 Value='<%# Eval("QuestionID") %>'></asp:HiddenField>
<asp:Label ID="lblQuesNum" runat="server" Font-Bold="True" 
 Text='<%# Eval("QuestionNum") %>'></asp:Label>
<asp:Label ID="Label2" runat="server" Font-Bold="True" 
 Text='<%# Eval("Question") %>'></asp:Label>
<asp:HiddenField ID="hiddenPicklistID" runat="server"  
 Value='<%# Eval("PicklistID") %>' />
<asp:HiddenField ID="HiddenField1" runat="server" 
 Value='<%# Eval("AnswerType") %>' />

<asp:DataList ID="DataList2" runat="server" DataSourceID="dsPicklist">
<ItemTemplate>
    <asp:HiddenField ID="hidPickID" runat="server" value='<%# Eval("PICKLISTID") %>' />
    <asp:Label ID="Label3" runat="server" Text='<%# Eval("TEXT") %>'></asp:Label> 
    <asp:HiddenField ID="HiddenField1" runat="server" 
     Value='<%# Eval("AnswerType") %>' />
 </ItemTemplate>
 </asp:DataList>
 </asp:TextBox>

Answer 1

不能将控件强制转换为数值。实际上，您希望将Hiddenfield的值强制转换为整数。

Dim hidden2 = DirectCast(e.Item.FindControl("HiddenField2"), HiddenField)
Dim QID As Integer = Int32.Parse(hidden2.Value)