如何在下拉菜單中將當前月份和年份設置爲默認值？

Question

我想在頁面加載期間在下拉列表中選擇當前月份和年份。 我試過了，但是當頁面加載時沒有在下拉列表中選擇該值，這裏有什麼問題？

到目前爲止，我已經做到了這一點：

<asp:DropDownList ID="ddlMonth" runat="server"> 
    <asp:ListItem Text="January" Value="01"></asp:ListItem> 
    <asp:ListItem Text="February" Value="02"></asp:ListItem> 
    <asp:ListItem Text="March" Value="03"></asp:ListItem> 
    <asp:ListItem Text="April" Value="04"></asp:ListItem> 
    <asp:ListItem Text="May" Value="05"></asp:ListItem> 
    <asp:ListItem Text="June" Value="06"></asp:ListItem> 
    <asp:ListItem Text="July" Value="07"></asp:ListItem> 
    <asp:ListItem Text="August" Value="08"></asp:ListItem> 
    <asp:ListItem Text="September" Value="09"></asp:ListItem> 
    <asp:ListItem Text="October" Value="10"></asp:ListItem> 
    <asp:ListItem Text="November" Value="11"></asp:ListItem> 
    <asp:ListItem Text="December" Value="12"></asp:ListItem> 
</asp:DropDownList> 

<asp:DropDownList ID="ddlYear" runat="server"> 
    <asp:ListItem Text="2010" Value="2010"></asp:ListItem> 
    <asp:ListItem Text="2011" Value="2011"></asp:ListItem> 
    <asp:ListItem Text="2012" Value="2012"></asp:ListItem> 
    <asp:ListItem Text="2013" Value="2013"></asp:ListItem> 
    <asp:ListItem Text="2014" Value="2014"></asp:ListItem> 
    <asp:ListItem Text="2015" Value="2015"></asp:ListItem> 
</asp:DropDownList> 

在我的頁面加載：

Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load 
    If Not Page.IsPostBack Then 
     'Select Current Month and Year to dropdowns 
     ddlYear.ClearSelection() 
     ddlMonth.ClearSelection() 
     Dim year As String = ddlYear.Items.FindByText(Format(Now, "yyyy")).ToString() 
     Dim month As String = ddlMonth.Items.FindByText(Today.ToString("MMMM")).ToString() 
     ddlYear.Items.FindByText(year).Selected = True 
     ddlMonth.Items.FindByText(month).Selected = True 
    End If 
End Sub 

Answer 1

您需要設置在下拉列表SelectedValue屬性不在列表中的項目，我相信。

Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load 
    If Not Page.IsPostBack Then 
     'Select Current Month and Year to dropdowns 
     ddlYear.ClearSelection() 
     ddlMonth.ClearSelection() 
     ddlYear.SelectedValue = ddlYear.Items.FindByText(Format(Now, "yyyy")).Value; 
     ddlMonth.SelectedValue = ddlMonth.Items.FindByText(Today.ToString("MMMM")).Value; 
    End If 
End Sub