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. mysql主从配置，读写分离

    Mysql主从配置,实现读写分离 大型网站为了软解大量的并发访问,除了在网站实现分布式负载均衡,远远不够.到了数据业务层.数据访问层,如果还是传统的数据结构,或者只是单单靠一台服务器扛,如此多的数据库 ...

  2. arc 093 D – Grid Components

    题意: 给出A和B,要求构造出一个具有A个白色连通块和B个黑色连通块的矩阵. 这个矩阵的长和宽最多为100. 思路: 试想如果横着每个点同类的点隔着一个不同的点,竖着每个同类的点隔着一个不同的点,那么 ...

  3. java 的Colections类（Java也有python类似列表的反转、排序等方法）

    1.Collections类概述         针对集合操作 的工具类,都是静态方法   2.Collections成员方法         public static <T> void ...

  4. 【函数封装】javascript判断是否是微信浏览器

    //判断是否是微信浏览器的函数 function isWeiXin(){ //window.navigator.userAgent属性包含了浏览器类型.版本.操作系统类型.浏览器引擎类型等信息,这个属 ...

  5. linux的错误码error

    在程序出错时,我们通过全局变量错误号errno和perror函数能够很快的定位到错误原因. Linux错误代码及其含义 C Name Value Description 含义Success 0 Suc ...

  6. gulp和webpack的区别

    一.概念 gulp 构建工具 我们可以通过给gulp配置不通的task(通过Gulp中的gulp.task()方法配置,比如启动server.sass/less预编译.文件的合并压缩等等)来让gulp ...

  7. Piggy-Bank HDU - 1114

    Before ACM can do anything, a budget must be prepared and the necessary financial support obtained. ...

  8. centos7 static for django2.1

    #user nobody; worker_processes 1; #error_log logs/error.log; #error_log logs/error.log notice; #erro ...

  9. amoeba_mysql 读写分离

    环境 amoeba需要java环境,配置:略. MySQL主从配置:略. 基本架构 MySQL主:192.168.31.140 MySQL从:192.168.31.150 MySQL代理:192.16 ...

  10. javascript 与 PHP 通信加密，使用AES 128 CBC no padding，以及ios，java,c#文章例子

    运行环境 php7.0 不适用于 php7.0以上版本,因为mcrypt_encrypt()函数已删除 为何要采用 no padding 这种形式: AES加密如果原输入数据不够16字节的整数位,就要 ...