What is difference between UniqueID and ClientID in ASP.Net Controls ?

Control.ClientID

ClientID will be a unique ID string that is rendered to the client to identify the control in the output HTML.

It uses _ to include parent controls (container) ID to make it unique.

For example, ct100_ContentPlaceHolder1_txtLogin. The client id for control will be generated by appending the parent container's(parent control) ID with the original control id with "_" as delimeter.

In our example, ContentPlaceHolder1 is the ContentPlaceHolder ID of the master page which is the parent container for txtLogin.

To get the ClientID of a control,
txtLogin.ClientID

The client id can be used to identify the control in client side scripting like javascript.
 
Control.UniqueID
UniqueID
is also a uniquely identifiable ID for a control but only used by
ASP.Net page framework to identify the control.

It uses $ to include
parent controls (container) ID to make it unique.

For example,
ct100$ContentPlaceHolder1$txtLogin. Similar to ClientID, UniqueID is
also generated by appending the parent container's(parent control) ID
with the original control id but with $ delimeter.

To get the UniqueID of a control,
txtLogin.UniqueID

The unique id is used by the Asp.Net framework to identify the control when the page is posted back to the server.

Why ClientID and UniqueID

Well, as you probably know UniqueID is used with name attribute and ClientId with id attribute of rendered HTML tag.

UniqueID uses colon as separator. On the other hand ClientId uses underscore as separator, because colon is not allowed in JavaScript variable names.

ClientID is indeed also unique on the Page as UniqueID is, but ClientID is targeted at client-side processing and UniqueID for server-side (pretty obvious),the latter especially to route for postback data and events with composite controls

However I think some reasoning might be that using underscore as separator in normal Control IDs is pretty common behavior and therefore underscore cannot be used in UniqueID as control separator (if we'd theoretically think managing with one property),because you couldn't make distinction between controls.

On the other hand for the same reasoning, you can't use colon in Control IDs, Page Framework does not allow it, so that it makes sure colons can't get to the ClientIDs (this was because of JavaScript does not like it).

And for these reasons, colon is pretty good choice to be used in UniqueID, because FindControl method can use it to navigate Control tree and locate controls (it can easily split the UniqueID).

Difference between ID and control.ClientID OR why use control.ClientID if I can access control through ID

问题

This is the code from .aspx file

<html xmlns="http://www.w3.org/1999/xhtml">

<head runat="server">

    <title>Login Again</title>

    <script type="text/javascript">

        function Validate() {

            if (document.getElementById("txtLogin").value == "") {

                alert("Enter login name.");

            }

            if (document.getElementById("<%=txtLogin.ClientID%>").value == "") {

                alert("Enter login name.");

            }

        }

    </script>

</head>

<body>

    <form id="form1" runat="server">

    <asp:TextBox ID="txtLogin" runat="server"></asp:TextBox>

    <asp:Button ID="btnSubmit" runat="server" Text="Login" OnClientClick="Validate()" />

    </form>

</body>

</html>

  • In function Validate() I can access textbox using Id of control i.e.; getElementById("txtLogin") so should I use the second approach which is accessing control through control.ClientID and why?

  • My first understanding was that to access server control I have to use this syntax <%= %> but now I come to know from this example that I can access server side control simply through getElementById("ID-of-control").

答案

The ID generated in the final HTML is not guaranteed to remain the same as the one in your aspx source.

When you'll put the controls inside naming containers the ID will have prepended one or several parent ids to ensure its uniqueness.

The ClientId property will always give you the final form of the ID attribute as it ends up in the HTML so it's always recommended to use that in your javascript.

ID vs UniqueID vs ClientID vs UniqueClientID vs StaticClientID?

  • The ID is the serverside ID that you use in your code.
  • The UniqueId corresponds to the "name" attribute of the generated HTML element.
  • The ClientID corresponds to the "id" attribute of the generated html element. So it depends which attribute you need (name is sent with form post, id is used for DOM manipulation).
  • Not sure what the uniqueclientid is :)

ASP.Net 4 adds clientIdMode which allows you to force the id attribute to match the serverside id (and thus be more predictable) if you set it to "static".

ASP.Net: ClientID not correct in code-behind of a user control

答案1

You should try moving the code that adds the onclick attribute to the button in the PreRender event (or OnPreRender override) in your page or user-control.

That should probably get the ClientID right.

答案2

I don't know which asp.net version you are using but in 4.0 you can declare inside any server control ClientIDMode="static" and it will give you the exact id in browser.

Example:

<asp:Textbox id="txtName" runat="server" ClientIdMode="static"/>

Others are predictable, inherit and it can be used with ClientIdRowsuffix.Can be used at page level and even on master pages and even in web.config file.

Example on web.config file:

<system.web>

<Pages clientIDMode="predictable"/>

other system web properties

</system.web>

Watched Craig shoemaker's Video at tekpub, you can also read more about it at Rick's bloglink text. It's pretty cool tho.

Difference between ID and control.ClientID OR why use control.ClientID if I can access control through ID的更多相关文章

  1. Method and system for implementing mandatory file access control in native discretionary access control environments

    A method is provided for implementing a mandatory access control model in operating systems which na ...

  2. Oracle Applications Multiple Organizations Access Control for Custom Code

    档 ID 420787.1 White Paper Oracle Applications Multiple Organizations Access Control for Custom Code ...

  3. Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' heade

    XMLHttpRequest cannot load http://10.164.153.37:8050/WebService/WebService.asmx/wsGetStreetData. Res ...

  4. SELINUX、Security Access Control Strategy && Method And Technology Research - 安全访问控制策略及其方法技术研究

    catalog . 引言 . 访问控制策略 . 访问控制方法.实现技术 . SELINUX 0. 引言 访问控制是网络安全防范和客户端安全防御的主要策略,它的主要任务是保证资源不被非法使用.保证网络/ ...

  5. Linux VFS Extended Attribute And Access Control Table

    catalog . 简介 . 扩展属性 . 访问控制表 . 小结 0. 简介 许多文件系统都提供了一些特性,扩展了VFS层提供的标准功能,虚拟文件系统不可能为所有特性都提供具体的数据结构.超出标准的U ...

  6. RBAC（Role-Based Access Control，基于角色的访问控制）

    RBAC(Role-Based Access Control,基于角色的访问控制),就是用户通过角色与权限进行关联.简单地说,一个用户拥有若干角色,每一个角色拥有若干权限.这样,就构造成“用户-角色- ...

  7. 转:Oracle R12 多组织访问的控制 - MOAC(Multi-Org Access Control)

    什么是MOAC MOAC(Multi-Org Access Control)为多组织访问控制,是Oracle EBS R12的重要新功能,它可以实现在一个Responsibility下对多个Opera ...

  8. RBAC（Role-Based Access Control)基于角色的访问控制

    RBAC(Role-Based Access Control,基于角色的访问控制),就是用户通过角色与权限进行关联.简单地说,一个用户拥有若干角色,每一个角色拥有若干权限.这样,就构造成"用 ...

  9. [认证授权] 6.Permission Based Access Control

    在前面5篇博客中介绍了OAuth2和OIDC(OpenId Connect),其作用是授权和认证.那么当我们得到OAuth2的Access Token或者OIDC的Id Token之后,我们的资源服务 ...

随机推荐

  1. uvm设计分析——field automation

    uvm中的field_automation主要实现了class中的基础元素的copy,compare等函数, 实现方式分为两种:1)用户注册,field系列宏:uvm内部调用static status ...

  2. DX9 DirectX键盘控制程序 代码

    // @time: 2012.3.26 // @author: jadeshu // des: DirectX键盘控制程序 #include <Windows.h> #include &l ...

  3. Sitecore CMS中配置模板部分

    如何在Sitecore CMS中配置模板部分. 注意: 本教程将扩展于“Sitecore CMS中创建模板”的章节. 配置折叠状态 配置模板部分的折叠状态允许用户选择默认折叠或展开哪些模板部分.此设置 ...

  4. Quick-Cocos2d-x文件结构分析

    在上一章我们讲过了Quick-Cocos2d-x中的环境搭建,这章我们分析下quick中的文件结构吧!打开quick的文件夹,可以看到如下的这些目录和文件: bin:存放各种与引擎相关的脚本 comp ...

  5. WordConuts

    import java.io.File; import java.io.FileNotFoundException; import java.util.HashMap; import java.uti ...

  6. SQLServer 比like好用的函数 charindex

    比如查找用户名包含有"c"的所有用户, 可以用 use mydatabase select * from table1 where username like'%c%" ...

  7. yield的理解

    yield的理解:yield命令是异步两个阶段的分界线需要先对迭代器和生成器进行理解: 迭代器:是一种支持next()操作的对象.它包含一组元素,当执行next()时,返回其中一个元素:当所有元素都被 ...

  8. python的一些遗漏用法

    一. 补充基础数据类型的相关知识点 1. str. join() 把列表变成字符串 li = ["李嘉诚", "麻花藤", "⻩海峰", & ...

  9. C++中虚函数的作用

    一, 什么是虚函数(如果不知道虚函数为何物,但有急切的想知道,那你就应该从这里开始) 简单地说,那些被virtual关键字修饰的成员函数,就是虚函数.虚函数的作用,用专业术语来解释就是实现多态性(Po ...

  10. EditPlus配置Java

    --Java Compile-- 命令:D:\Program Files\Java\jdk1.7.0_79\bin\javac.exe 参数:$(FileName) 初始目录:$(FileDir) 动 ...