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. ling join 报错The specified LINQ expression contains references to queries that are associated with different cont

    The specified LINQ expression contains references to queries that are associated with different cont ...

  2. 如何重置Sitecore CMS中的管理员密码

    在Sitecore项目上工作时,有时管理员凭据会丢失或损坏.在这些情况下,重新获得快速访问权限以便不中断开发非常重要. 对Core数据库运行以下查询,您将能够admin/b再次使用以下命令登录Site ...

  3. C#操作XML方法详解

    using System.Xml; //初始化一个xml实例 XmlDocument xml=new XmlDocument();   //导入指定xml文件 xml.Load(path); xml. ...

  4. 【Hadoop学习之十一】MapReduce案例分析三-PageRank

    环境 虚拟机:VMware 10 Linux版本:CentOS-6.5-x86_64 客户端:Xshell4 FTP:Xftp4 jdk8 hadoop-3.1.1 什么是pagerank?算法原理- ...

  5. python range函数

    这个函数很简单,就不写例子了,看看语法,拿来即用 python range() 函数可创建一个整数列表,一般用在 for 循环中. 函数语法 range(start, stop[, step]) 参数 ...

  6. java运行cmd命令

    java的Runtime.getRuntime().exec(commandStr)可以调用执行cmd指令. cmd /c dir 是执行完dir命令后关闭命令窗口. cmd /k dir 是执行完d ...

  7. sqlyog连接Linux上的mysql报错误号码2013，错误号码1130的解决办法

    sqlyog连接Linux上的mysql报错误号码2013,错误号码1130的解决办法 1.报错误号码2013,可能是端口号不是默认的3306,需要改成对应的,检查命令是: [root@host et ...

  8. Andriod post Api与返回值

    vs后台api控制器  post接收参数----HttpContext.Current.Request.Params["account"].ToString() 返回值为对象返回, ...

  9. 使用Holer外网SSH访问内网（局域网）Linux系统

    1. Holer工具简介 Holer exposes local servers behind NATs and firewalls to the public internet over secur ...

  10. dubbo原理

    1,观察DubboBeanDefinitionParser 的构造方法,给它打一个断点,发现其前一步在DubboNamespaceHandler 应用启动会连续调此方法 DubboBeanDefini ...