回发后，dropdownlist不显示任何值 [英] dropdownlist does not show any values after postback

问题描述

大家好，

我有一个使用webforms的网络应用程序，我在Formview中有两个下拉列表。

我根据选择来填充一个下拉列表其他。只要没有发生回发，我就会看到列表正确填充但在回发后，我的下拉列表是空的。

我正在设置我在运行时填充的ddl的DataValueField属性该ddl的ViewStateMode设置为Enabled。

有谁知道原因是什么？

非常感谢。

Hi everyone,
I have a web application using webforms and I have two dropdown lists inside a Formview.
I am populating one dropdownlist based on the selection from the other. As long as there is no postback happening, I see the list getting populated correctly but after a postback, my dropdownlist is empty.
I am setting the DataValueField property of the ddl that I populate at runtime and the ViewStateMode for that ddl is set to Enabled.
Does anyone know what could be the reason?
Thanks much.

推荐答案

我强烈怀疑你在Page_Load事件中绑定了DropDownList。如果是这样，请按如下所示：

I strongly suspect you binded your DropDownList in Page_Load event. If so,put it as follows:

protected void Page_Load(object sender, EventArgs e)
{
   if (!IsPostBack)
   {
         //bind dropdown here
   }
}

问候......

你指的是基于我填充其他ddl的ddl吗？我在if（！postback）中绑定了那个，但是另一个没有绑定。

我注意到在运行时填充的文本框的内容也会在回发后消失。

我将ddl移到了Formview之外，现在它在回发后保留了它的内容。

Formview中控件的具体内容在运行时填充，我怎么能让它们在回发后保留它们的值？

谢谢。

Are you referring to the ddl based on which I am populating the other ddl? I do bind that one in if(!postback) but the other one is not bound at all.
I noticed that the contents of a text box that is filled at runtime also disappear after postback.
I moved the ddl outside of the Formview and now it retains its contents after postback.
What is specific about controls inside a Formview that are filled at runtime and how can I make them retain their values after postback?
Thanks.

这篇关于回发后，dropdownlist不显示任何值的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！