[英]Dropdownlist binding data again on postback even with Page.IsPostback
我需要列出所有列出的商店。 當點擊需要獲取所選值但發生回發時,即使我檢查Page.IsPostback它總是為null,因為沒有數據。
這是我的代碼。
=============================================
<div id="SurveyCompetitionContainer">
<div class="surveyCompetitionContents">
<ajax:UpdatePanel ID="WinSurveyAjax" runat="server" UpdateMode="conditional" ChildrenAsTriggers="true"
RenderMode="block">
<ContentTemplate>
<div id="competitionInfo" runat="server" visible="true">
<div class="headerTitle">
Enter your email for the chance to win a week long holiday in a luxury apartment
in the Lake District.
</div>
<div class="emailBox">
<div class="emailDiv">
<asp:Label ID="emailLabel" CssClass="emailLabel" Text="Email:" runat="server"></asp:Label>
<asp:TextBox ID="emailTextbox" runat="server" CssClass="water" Text="" ClientIDMode="Static"
ValidationGroup="EmailGroup"> </asp:TextBox>
</div>
<div class="storesDiv">
<asp:Label ID="LabelStores" CssClass="StoreLabel" Text="Your favourite Mountain Warehouse store:"
runat="server"></asp:Label>
<asp:DropDownList ID="Stores" CssClass="storesDD" runat="server" ToolTip="Stores"
EnableViewState="true" AppendDataBoundItems="True" OnSelectedIndexChanged="Stores_SelectedIndexChanged">
</asp:DropDownList>
</div>
</div>
<div class="enterbtn">
<asp:Button ID="emailJoinButton" CssClass="emailJoinButton" runat="server" OnClick="emailJoinButton_Click"
Text="ENTER" EnableViewState="False" ValidationGroup="EmailGroup" />
</div>
</div>
<div id="competitionSurvey" runat="server">
<div class="SCHeaderInfo">
<h2>
Thank you! We will notify the lucky winner by email.
</h2>
<h3>
We'd love to send you tailored special offers - just take a few moments to fill
out the following optional details.
</h3>
</div>
<div class="SCquestionsDetails">
<p>
<b>1. What are you interested in?</b><span class="small"> (Select all that apply)</span></p>
<asp:CheckBoxList ID="Interests" runat="server" CssClass="interests" Width="400">
<asp:ListItem>Camping</asp:ListItem>
<asp:ListItem>Hiking</asp:ListItem>
<asp:ListItem>Skiing</asp:ListItem>
<asp:ListItem>Travel</asp:ListItem>
<asp:ListItem>Walking</asp:ListItem>
<asp:ListItem>Everything</asp:ListItem>
<asp:ListItem>Mens</asp:ListItem>
<asp:ListItem>Womens</asp:ListItem>
<asp:ListItem>Kids</asp:ListItem>
</asp:CheckBoxList>
</div>
</div>
</ContentTemplate>
</ajax:UpdatePanel>
</div>
</div>
================================
protected void Page_Load(object sender, EventArgs e)
{
if (!Page.IsPostBack)
BindAllStores();
}
protected void emailJoinButton_Click(object sender, EventArgs e)
{
Session["FavStore"] = Stores.SelectedItem.ToString(); --> this is where i am storing the selected value.
if (Page.IsValid)
{
if (competitionInfo.Visible == true)
{
LoadSurvey();
competitionInfo.Visible = false;
competitionSurvey.Visible = true;
}
}
}
public void BindAllStores()
{
Stores.AppendDataBoundItems = true;
Stores.Items.Add(new ListItem("--- Choose one of our stroes --- ", "0"));
Stores.DataSource = AllStores;
Stores.DataTextField = "DisplayName";
Stores.DataValueField = "NAME";
Stores.DataBind();
}
我正在做的是我在點擊時隱藏了一個div,並顯示了所有調查問題的另一個div,並且在提交時我需要獲得前一個具有下拉列表的div的值。
請幫助我,因為我發現它很困難。
謝謝大家。
首先,在ASPX中的AsyncPostBackTrigger
中指定DropDownList
<Triggers>
<asp:AsyncPostBackTrigger ControlID="dropdownlist" EventName="SelectedIndexChanged" />
</Triggers>
其次,嘗試使用IsInAsyncPostBack
:
protected void Page_Load(object sender, EventArgs e)
{
if (!ScriptManager.GetCurrent(Page).IsInAsyncPostBack)
{
BindAllStores();
}
}
啟用您的頁面和DropDownlist viewState
然后嘗試
視圖狀態使服務器控件能夠跨HTTP請求維護其狀態。 如果滿足以下所有條件,則啟用控件的視圖狀態:
或者在control / page init中加載數據(不要檢查IsPostBack標志)而不是pageLoad
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