Home > Others

Control contains code blocks, so the control set cannot be modified.

Source: Internet
Author: User
Developer on Alibaba Coud: Build your first app with APIs, SDKs, and tutorials on the Alibaba Cloud. Read more ＞

Original http://www.cnblogs.com/jsonzheng/archive/2011/01/18/1938403.html

Control contains code blocks (that is, <%... %>), so the control set cannot be modified.
Note: An unhandled exception occurs during the execution of the current Web request. Check the stack trace information for details about the error and the source of the error in the code.
Exception details: System. Web. HttpException: Control contains code blocks (namely, <%... %>), so the control set cannot be modified.
I. Error example explanation:
<Asp: Panel ID = "p_Time" runat = "server">
<% = DateTime. Now. ToString ("HH-mm") %>
</Asp: Panel>

Label lb = new Label ();
Lb. Text = "Current Time ";
P_Time.Controls.Add (lb );
This error occurs when the preceding code is executed. Because the p_Time control contains a code block (namely <%... %>), the control set cannot be modified. Therefore, an error occurs when the statement p_Time.Controls.Add (lb) is executed.

2. Common Errors and Solutions
Generally, in the javascript code of the header of the page code, <% = this. control. clientID %> to obtain the Server Control identifier (the Code is as follows). When the topic and other functions are applied, the server script dynamically adds the control to the Header, causing an error .?
<html xmlns="http://www.w3.org/1999/xhtml">   <head runat="server">      <script type="text/javascript">      function showTime()      {         var now = new Date();         var lbTime = document.getElementById('<%= this.lb_Time.ClientID %>');         lbTime.innerHTML = now.getHours() + ":" + now.getMinutes();      }      </script>   </head>   <body>      <asp:Label ID="lb_Time" runat="server" Text="lb_Time"></asp:Label>      <input id="btn_Show" type="button" value="button" onclick="return showTime()" />   </body></html>

The solution is as follows:

1. Place javascript in the body.
2. Declare a custom control to replace the code block (that is, <%... %>)
Control Code :?
public class ControlInfoWriter : Control{   private string writerControlID;   private string writerProperty;    public string WriterControlID   {       get { return writerControlID; }       set { writerControlID = value; }   }    public string WriterProperty   {       get { return writerProperty; }       set { writerProperty = value; }   }    protected override void Render(System.Web.UI.HtmlTextWriter writer)   {       object writerControl = this.Parent.FindControl(writerControlID);// Search for the control to be output       Type t = writerControl.GetType();// Obtain the control type       PropertyInfo pi = t.GetProperty(writerProperty);// Obtain the attribute to be output       string value = pi.GetValue(writerControl, null).ToString();// Obtain the property value of the control.       writer.Write(value);       base.Render(writer);   }}

The javascript modification in head is as follows :?

<script type="text/javascript">function showTime(){   var now = new Date();   var lbTime = document.getElementById('<CustomControl:ControlInfoWriter
ID="controlInfoWriter" WriterControlID="lb_Time"
WriterProperty="ClientID" runat="server" />');   lbTime.innerHTML = now.getHours() + ":" + now.getMinutes();}</script>

Note: The mcontrol: ControlInfoWriter control must be registered in the page code.

Author: Zheng Ren
Source: http://jsonzheng.cnblogs.com
You are welcome to repost or share it, but be sure to declare the source of the article. If the article is helpful to you, I hope you can recommend it or follow it.

This article is an English version of an article which is originally in the Chinese language on aliyun.com and is provided for information purposes only. This website makes no representation or warranty of any kind, either expressed or implied, as to the accuracy, completeness ownership or reliability of the article or any translations thereof. If you have any concerns or complaints relating to the article, please send an email, providing a detailed description of the concern or complaint, to info-contact@alibabacloud.com. A staff member will contact you within 5 working days. Once verified, infringing content will be removed immediately.

Contact Us

The content source of this page is from Internet, which doesn't represent Alibaba Cloud's opinion; products and services mentioned on that page don't have any relationship with Alibaba Cloud. If the content of the page makes you feel confusing, please write us an email, we will handle the problem within 5 days after receiving your email.

If you find any instances of plagiarism from the community, please send an email to: info-contact@alibabacloud.com and provide relevant evidence. A staff member will contact you within 5 working days.

A Free Trial That Lets You Build Big!

Start building with 50+ products and up to 12 months usage for Elastic Compute Service

Get Started for Free

  • Sales Support

    1 on 1 presale consultation

    Chat Contact Sales

  • After-Sales Support

    24/7 Technical Support 6 Free Tickets per Quarter Faster Response

    Open a Ticket

  • Alibaba Cloud offers highly flexible support services tailored to meet your exact needs.

    Learn More