Declaring asp.net control inside HTML markup - asp.net

Question

Is it possible to write something like this?
<input class="form-control" id="name" name="name"
placeholder='<asp:Label runat="server" ID="lblFormName"></asp:Label>' type="text" required autofocus />

Answer 1

Solution 1: let ASP.Net render extra attributes
You can use the native TextBox control :
<asp:TextBox runat="server"
ID="name"
required="required"
autofocus="autofocus"
CssClass="form-control"
placeholder="myplaceholder" />
Extra attributes (ones that are not properties of the TextBox class), will be rendered as is:
Html result:
<input name="ctl00$MainContent$name"
type="text"
id="MainContent_name"
class="form-control"
required="required"
autofocus="autofocus"
placeholder="myplaceholder" />
If the generated id must be explicit, you can add CliendIDMode="Static":
<asp:TextBox runat="server"
ID="name"
required="required"
autofocus="autofocus"
CssClass="form-control"
placeholder="myplaceholder"
ClientIDMode="Static" />
Result:
<input name="ctl00$MainContent$name"
type="text"
id="name"
class="form-control"
required="required"
autofocus="autofocus"
placeholder="myplaceholder" />
Solution 2: write your own control
An even better approach is to extend the textbox class:
using System.Web.UI.WebControls;
namespace WebApplication1.Controls
{
public class TextBoxEx : TextBox
{
protected override void AddAttributesToRender(System.Web.UI.HtmlTextWriter writer)
{
if (AutoFocus) writer.AddAttribute("autofocus", "autofocus");
if (Required) writer.AddAttribute("required", "required");
if (!string.IsNullOrEmpty(PlaceHolder)) writer.AddAttribute("placeholder", PlaceHolder);
base.AddAttributesToRender(writer);
}
public string PlaceHolder
{
get {
var obj = ViewState["PlaceHolder"];
return obj != null ? (string)obj : default(string);
}
set { ViewState["PlaceHolder"] = value; }
}
public bool AutoFocus
{
get {
var obj = ViewState["AutoFocus"];
return obj != null ? (bool)obj : default(bool);
}
set { ViewState["AutoFocus"] = value; }
}
public bool Required
{
get {
var obj = ViewState["Required"];
return obj != null ? (bool)obj : default(bool);
}
set { ViewState["Required"] = value; }
}
}
}
Then you can register and use the control:
<%# Register Assembly="WebApplication1" TagPrefix="local" Namespace="WebApplication1.Controls" %>
....
<local:TextBoxEx runat="server" required="true" autofocus="true" PlaceHolder="my placeholder" />

Answer 2

You want to assign some value to one of HTML element's properties?
<asp:HiddenField runat="server" ID="lblFormName" />
<input class="form-control" id="name" name="name" placeholder='<%# lblFormName.Value %>' ...
Then you pass lblFormName.Value from CodeBehind.

Answer 3

You cannot declare a single ASP.NET control in a pure HTML page. It must be a ASP.NET page (aspx) which is processed by the server.