HtmlForm Server Control Declarative Syntax
Creates a server-side control that maps to the <form> HTML element and allows you to create a container for elements in a Web page.
<form
DefaultButton="string"
DefaultFocus="string"
EnableViewState="False|True"
Id="string"
SubmitDisabledControls="False|True"
Visible="True|False"
OnDataBinding="OnDataBinding event handler"
OnDisposed="OnDisposed event handler"
OnInit="OnInit event handler"
OnLoad="OnLoad event handler"
OnPreRender="OnPreRender event handler"
OnUnload="OnUnload event handler"
runat="server"
>
<!--Other controls, input forms, and so on.-->
</form>
Remarks
Use the HtmlForm control to program against the HTML <form> element. To take advantage of postback services, all Web Forms controls, whether HTML controls, Web controls, user controls, or custom controls, must be nested between well-formed opening and closing tags of the HtmlForm control. If the tags are not closed properly, ASP.NET will not recognize the element. Either the element will be ignored or a compilation error will occur, depending on how the element is formed.
.gif) Note |
|---|
You cannot include more than one HtmlForm control on a single Web Forms page. |
By default, the HtmlForm control's method attribute is set to POST. You can customize the method attribute to suit your needs, but setting the method attribute to a value other than GET or POST can break the built-in view state and postback services provided by ASP.NET.
| Note |
|---|
The action attribute is always set to the URL of the page itself. The action attribute cannot be changed; therefore, you can only post back to the page itself. |
Example
The following example shows three HtmlButton controls with a separate OnServerClick handler for each button. Each of these events causes a postback to the server (the HtmlForm control is required for any scenario in which a postback occurs). This example also demonstrates that only one HtmlForm control is allowed on a Web Forms page, including a form that supports multiple events. If you include more than one HtmlForm control, the .NET Framework will throw an exception.
<%@ Page Language="VB" AutoEventWireup="True" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head>
<title>HtmlForm Control</title>
<script runat="server">
Sub Button1_OnClick(Source As Object, e As EventArgs)
Span1.InnerHtml = "You clicked Button1"
End Sub
Sub Button2_OnClick(Source As Object, e As EventArgs)
Span2.InnerHtml = "You clicked Button2"
End Sub
Sub Button3_OnClick(Source As Object, e As EventArgs)
Span3.InnerHtml = "You clicked Button3"
End Sub
</script>
</head>
<body>
<h3>HtmlForm Sample</h3>
<form id="ServerForm" runat="server">
<button id="Button1" runat="server"
onserverclick="Button1_OnClick">
Button1
</button>
<span id="Span1" runat="server" />
<p />
<button id="Button2" runat="server"
onserverclick="Button2_OnClick">
Button2
</button>
<span id="Span2" runat="server" />
<p />
<button id="Button3" runat="server"
onserverclick="Button3_OnClick">
Button3
</button>
<span id="Span3" runat="server" />
</form>
</body>
</html>
<%@ Page Language="C#" AutoEventWireup="True" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head>
<title>HtmlForm Control</title>
<script runat="server">
void Button1_OnClick(object Source, EventArgs e)
{
Span1.InnerHtml="You clicked Button1";
}
void Button2_OnClick(object Source, EventArgs e)
{
Span2.InnerHtml="You clicked Button2";
}
void Button3_OnClick(object Source, EventArgs e)
{
Span3.InnerHtml="You clicked Button3";
}
</script>
</head>
<body>
<h3>HtmlForm Sample</h3>
<form id="ServerForm" runat="server">
<button id="Button1" runat="server"
onserverclick="Button1_OnClick">
Button1
</button>
<span id="Span1" runat="server" />
<p />
<button id="Button2" runat="server"
onserverclick="Button2_OnClick">
Button2
</button>
<span id="Span2" runat="server" />
<p />
<button id="Button3" runat="server"
onserverclick="Button3_OnClick">
Button3
</button>
<span id="Span3" runat="server" />
</form>
</body>
</html>