javascript HiddenField 值在回发时丢失
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HiddenField Value Lost on Postback
提问by Jonathan Wood
I have some JavaScript that sets the value of a HiddenFieldand then forces a postback. I can trace through this JavaScript and it appears to work correctly. However, when I test the value of the HiddenFieldfrom the page's Load event, it is no longer set.
我有一些 JavaScript 可以设置 a 的值，HiddenField然后强制回发。我可以跟踪这个 JavaScript，它似乎可以正常工作。但是，当我HiddenField从页面的 Load 事件中测试 的值时，它不再被设置。
Searching the web, I see a lot of posts about losing HiddenFieldvalues but none of them seemed to be doing the same thing that I am.
在网上搜索，我看到很多关于失去HiddenField价值的帖子，但似乎没有一个和我在做同样的事情。
Here's my JavaScript function (modified):
这是我的 JavaScript 函数（已修改）：
function EditItemItem(itemId) {
document.getElementById('<%= EditItemId.ClientID %>').value = itemId;
__doPostBack('<%= EditItemUpdatePanel.ClientID %>', '');
}
And here's part of my markup (modified):
这是我标记的一部分（已修改）：
<div id="EditItemBox" runat="server">
<asp:HiddenField runat="server" id="EditItemId" />
<asp:UpdatePanel ID="EditItemUpdatePanel" runat="server"
UpdateMode="Conditional">
<ContentTemplate>
<asp:Panel ID="EditItemPanel" runat="server"
CssClass="ModalDialog" style="display:none;">
<div>Edit an Item</div>
<!-- ... -->
</asp:Panel>
</asp:UpdatePanel>
</div>
Does anyone have any ideas?
有没有人有任何想法？
回答by marto
It's easier if you remove runat=serverfrom the hidden field and then access it from the Form paramaters Request.Form["EditItemId"]. Then it works every time.
如果您runat=server从隐藏字段中删除然后从 Form 参数中访问它会更容易Request.Form["EditItemId"]。然后它每次都有效。
Your code will become:
您的代码将变为：
function EditItemItem(itemId) {
document.getElementById('EditItemId').value = itemId;
__doPostBack('<%= EditItemUpdatePanel.ClientID %>', '');
}
<div id="EditItemBox" runat="server">
<input type="hidden" id="EditItemId" name="EditItemId" value="" />
<asp:UpdatePanel ID="EditItemUpdatePanel" runat="server"
UpdateMode="Conditional">
<ContentTemplate>
<asp:Panel ID="EditItemPanel" runat="server"
CssClass="ModalDialog" style="display:none;">
<div>Edit an Item</div>
<!-- ... -->
</asp:Panel>
</asp:UpdatePanel>
</div>
回答by Kieron
If you're expecting the value upon an AJAX post-back via the UpdatePanelthen you need to put it inside the ContentTemplate...
如果您期望通过 AJAX 回传的值，UpdatePanel那么您需要将其放入ContentTemplate...
