ASP.NET下拉列表-C＃.NET和JavaScript
[英]asp.net dropdownlist - C#.NET and javascript
问题描述
I have a drop down and a div right next to it. 
我旁边有一个下拉菜单和一个div。 The text contained inside the div should be updated based on value selected in the dropdown. div中包含的文本应根据下拉菜单中选择的值进行更新。
I do NOT want to use AutoPostBack feature. 我不想使用AutoPostBack功能。
3 个解决方案
解决方案1
2 2009-12-08 22:14:04
Use OnChange client side event of the dropdownlist control. 使用下拉列表控件的OnChange客户端事件。 Here is a sample that updates a div's inner text with the selected value of the dropdown list : 这是一个示例，该示例使用下拉列表的选定值更新div的内部文本：
<asp:DropDownList runat="server" ID="myDDL"
OnChange="document.getElementById('myDiv').innerText=this.value;">
</asp:DropDownList>
<div id="myDiv"></div>
解决方案2
1 2009-12-08 22:47:34
As people have said, you cannot access the C# codebehind code without performing a postback. 正如人们所说的那样，如果不执行回发操作，则无法访问C＃代码隐藏代码。
One way of accomplishing what you want is to use PageMethods. 完成所需内容的一种方法是使用PageMethods。 This is the Microsoft idiom for accomplishing this but there are lots of other Ajax libraries that will do it. 这是完成此操作的Microsoft习惯用法，但是还有许多其他的Ajax库可以完成此操作。
Provide a static method in your codebehind which will get called form your dropdownlist OnChange event. 在代码背后提供一个静态方法，该方法将从您的dropdownlist OnChange事件中调用。
[WebMethod]
public static string MyMethod()
{
// Your code goes here
return "The text for the div"
}
You then call this PageMethod from your .aspx page: 然后，从.aspx页调用此PageMethod：
You need to add a scriptmanager (after the form tag) 您需要添加一个脚本管理器（在表单标签之后）
<asp:ScriptManager ID="scriptmanager1" EnablePageMethods="true" EnablePartialRendering="true" runat="server" ></asp:ScriptManager>
Then in the OnChange event (or a function called from it) you have: 然后在OnChange事件（或从中调用的函数）中，您将：
<asp:DropDownList id="ddl" runat="server" OnChange="PageMethods.MyMethod(OnComplete);" />
Where OnComplete is a javascript function that handlers the PageMethod response: 其中OnComplete是用于处理PageMethod响应的javascript函数：
<script language="javascript">
function OnComplete(result, userContext, methodName) {
document.getElementById(yourDivId').innerText=result;
}
</script>
You can also have a paramaterised webmethod if needed: 如果需要的话，您还可以使用parametrisated web方法：
[WebMethod]
public static string MyMethod(string myNeatParam)
{
// Your code goes here
return "The text for the div"
}
And call it with: 并调用：
PageMethods.MyMethod('SomeValue', OnComplete)
解决方案3
0 2009-12-08 22:13:17
Updated based on comments: 根据评论更新：
Here's a sample page on using an UpdatePanel to do what you need to do. 这是有关使用UpdatePanel执行所需操作的示例页面。 Please keep in mind though that there is a full postback happening, even though it is transparent to the user. 请记住，即使对用户透明，也会发生完整的回发。
<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="UpdatePanelMadness._Default" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title></title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:ScriptManager ID="ScriptManager1" runat="server" />
<asp:UpdatePanel ID="UpdatePanel1" runat="server">
<ContentTemplate>
<asp:DropDownList ID="ColorsDropDownList" runat="server" AutoPostBack="true"
onselectedindexchanged="ColorsDropDownList_SelectedIndexChanged">
<asp:ListItem Text="Red" Value="Red" />
<asp:ListItem Text="Green" Value="Green" />
<asp:ListItem Text="Blue" Value="Blue" />
</asp:DropDownList>
<div id="ColorDiv" runat="server">
<p>
Hello World!
</p>
</div>
</ContentTemplate>
</asp:UpdatePanel>
</div>
</form>
</body>
</html>
code behind: 后面的代码：
namespace UpdatePanelMadness
{
using System;
public partial class _Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
}
protected void ColorsDropDownList_SelectedIndexChanged(object sender, EventArgs e)
{
ColorDiv.InnerText = this.ColorsDropDownList.SelectedValue;
}
}
}
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