ASP.NET Web Form

All server controls must be within the <form> tag, and the <form> tag must contain the runat="server" attribute.

ASP.NET Web Form

All server controls must be within the <form> tag, and the <form> tag must contain the runat="server" attribute. The runat="server" attribute indicates that the form must be processed on the server. It also indicates whether the controls loaded into it can be accessed by server scripts:

<form runat="server">...HTML + server controls</form>

Note:The form always submits to its own page. If you specify an action attribute, it will be ignored. If you omit the method attribute, it will be set to method="post" by default. At the same time, if you do not specify the name and id attributes, they will be automatically assigned by ASP.NET.

Note:A .aspx can only contain one <form runat="server"> control!

If you view the source code of a .aspx page and the form does not have name, method, action, or id attributes, you will see that ASP.NET has added these attributes to the form. Similar to this:

<form name="_ctl0" method="post" action="page.aspx" id="_ctl0">...some code</form>

Submit Form

Forms are usually submitted by clicking a button. The format of the Button server control in ASP.NET is as follows:

<asp:Button id="id" text="label" OnClick="sub" runat="server" />

The id attribute defines a unique name for the button, while the text attribute assigns a label to the button. The onClick event handler specifies a subroutine to be executed.

In the following example, we declare a button control in a .aspx file. One mouse click can run a subroutine and change the text on the button.

Display This Example