Hi could any one help me regarding the accessibility of HTML controls to Server Side ?
You should add runat="server" attribute to your HTML elements to access them at server side.
Have a look at this article:
http://odetocode.com/articles/348.aspx
You can add runat="server" and use controls in System.Web.UI.HtmlControls namespace to access it.
Related
I have an aspx page and controls on it. For the purpose consuming it at client side javascript I would like to place attributes for my elements. I would like to do it all in the markup, not in code behind. It seems the placed attributes will be all lowercased at client side.
For example:
<asp:LinkButton ID="anyButton" runat="server" confirmationMessage='any message'...
will be rendered at client side as:
<a confirmationmessage='any message'...
Consequently I must use this casing all my javascript code. Not a big issue, but quite disturbing if you like strict naming conventions.
Thanks in advance
Could you explain me the difference between controls and html components with the "runat=server" attribute. What is best practice to use it? Thanks.
<span runat="server" id="myspan"> </span>
maps to the GenericControl class defined in System.Web.UI.HtmlControls. From it's msdn description:
The System.Web.UI.HtmlControls namespace contains classes that allow
you to create HTML server controls on a Web Forms page. HTML server
controls run on the server and map directly to standard HTML tags
supported by most browsers. This allows you to programmatically
control the HTML elements on a Web Forms page.
<asp:Label runat="server" id="asplabel"></asp:Label>
maps to the Label class in System.Web.UI.WebControls. From it's msdn description
The System.Web.UI.WebControls namespace contains classes that allow
you to create Web server controls on a Web page. Web server controls
run on the server and include form controls such as buttons and text
boxes. They also include special-purpose controls such as a calendar.
Because Web server controls run on the server, you can
programmatically control these elements. Although Web server controls
are rendered as HTML, their object model does not necessarily reflect
HTML syntax.
The System.Web.UI.WebControls namespace contains classes that are
rendered as HTML tags, such as the TextBox control and the ListBox
control. The namespace also contains classes that are not rendered on
the Web page, but support data operations, such as the SqlDataSource
and ObjectDataSource classes. Other controls, such as the GridView and
DetailsView controls, support data display and editing. The WebControl
class serves as the base class for many of the classes in the
System.Web.UI.WebControls namespace.
Basically the controls from the WebControl namespace gives you more features where the design aim was to mimic VB6 forms as closely as possible to make the transition (back asnd forth) between winclient and webclient programming seamlessly.
I personally tend to use controls from the WebControls namespace as much as possible and only fallback to the HtmlConttols if I need behavior that is not availbale on a WebControl and not overrideable.
A blog from K. Scot Allen on the same topic
Server controls are tags that are understood by the server.
There are three kinds of server controls:
HTML Server Controls- Traditional HTML tags
Web Server Controls - New ASP.NET tags
Validation Server Controls - For input validation
HTML Server Control:
HTML elements in ASP.NET files are, by default, treated as text. To make these elements programmable, add a runat="server" attribute to the HTML element.
Example:
<form runat="server">
......
</form>
Web Server Controls:
Web server controls are special ASP.NET tags understood by the server.
Like HTML server controls, Web server controls are also created on the server and they require a runat="server" attribute to work. However, Web server controls do not necessarily map to any existing HTML elements and they may represent more complex elements.
Example:
<asp:Button ID="but" runat="server"/>
Validation Server Controls:
Validation server controls are used to validate user-input. If the user-input does not pass validation, it will display an error message to the user.
Example:
<asp:RequiredFieldValidator ID="req1" runat="server" ControlToValidator="TextBox1" ErrorMessage="please enter proper details"/>
I wonder, why do I have to include runat="server" to server elements in ASP.NET when runat only has one option and it is required for server elements. If not added it keeps telling me "missing a required attribute 'runat'".
Am I missing something here?
The runat="server" is there to let ASP.NET know which parts of your HTML is controlled server-side and which parts are not.
Please note that even standard HTML elements like <table> can have a runat="server", which then exposes it to your code.
Here is a previous StackOverflow question that has input from some people at Microsoft as to why the runat="server" tag is explicitly necessary for server tags, while causing errors if omitted.
Why does ASP.NET webforms need the Runat=“Server” attribute?
When don't you need to use runat="server" in ASP.NET?
EDIT: Thanks for all the answers, but I was really thinking of runat="server" inside an <asp: tag.
Use the runat=server attribute when you're using ASP.NET controls, and/or you require programmatic access to those controls in your code-behind.
HTML controls don't require this attribute. It's useful if you have any HTML element like <span> <div>, or <table> when you want the ability to access them in code-behind.
<asp:Label runat="server" id="foo" />
<div runat="server" id="bar />
...
foo.Text = "Hello Label";
foo.Attributes["class"] = "baz";
You need to use runat="server" on any control that you want to be parsed as a server control.
Any element with runat="server" will be parsed into a server control in the Page herarchy. Anything else will be handled as plain text, and put in LiteralControl controls in the Page hierarchy.
The exception is elements that aren't real elements, but special tags within another server tag, for example ContentTemplate tags. They don't need a runat="server" because the containing control will parse them.
When you don't want the server side ASP.NET to render a server side variable against us.
Generally speaking you don't use it when you don't need to manipulate the DOM element at the server side e.g. which are only used for layout purposes.
Without runat="server" there would also be no other way to make html controls server side controls. It does look like an odd thing, because you can't do runat="client".
So in summation you can't leave it out on any ASP .Net controls ever and it was probably the easiets and cleanest way to find all server side controls for the developers who created ASP .Net Web forms.
source: http://mikeschinkel.com/blog/whyrunatserverforaspnetpart2/
Tag runat="server" indicates that the code contained within the script block will run on the server (and not on the client). On execution, ASP.NET will create server-side objects that contain this code as well as an instance of the Page class to contain the controls defined inside the page as instances of their given type (System.Web.UI.WebControls.Textbox, for example). This server-side object will be invoked on user request and will execute code in response to events.
Create Control in Runtime
I need one label in runtime that time don't need runat="Server" is not required
Example
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
Label lblNew = new Label();
lblNew.ID ="lblnew";
lblNew.Text ="Test";
}
}
this code create label in runtime at page load event
see here this error - http://validator.w3.org/check?verbose=1&uri=http%3A%2F%2Fwww.sitecore.net%2F
runat="server" is asp.net server control syntax. It must not come in html. It is interpreted by ASP.NET. you must remove this attribute.
Possible Reason for this:
1. I think the template is dynamically created. the developer make static site and cut copy paste on server side to make it dynamic but use control as response.write and forgot to remove runat="server" because it must be html content in response.write.
NOTE: No ASP.NET server control gives runat="server" in HTML. It is hardcoded in your code. remove this from both anchor and image tag.
Er... remove the attributes? They aren't valid HTML, and they're only meaningful when interpreted by ASP.NET.
Your pages should not be rendered with runat="server", so something's definitely going wrong here. What does the part of your aspx look like, that corresponds to one of the elements that is giving this validation error?