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Usefulness of View State

One situation in which view state is important is form validation.

Suppose a user registration form is created with several required form fields i.e. you do not want anyone to submit the form without entering the first and the last name. If by chance someone has submitted the user registration form without completing the required form fields. In such a situation, you would like to display an appropriate error message. Further, you would like to re-display all the form information that the user had already entered, as no user would like to start from the scratch again.

Therefore View State automatically preserves the form information that the user enters.

Structure of an ASP.NET Page

Let us examine the main elements of a typical ASP.NET page. The following are the important parts of an ASP.NET page:

Directives
Code declaration block
Code render block
ASP.NET controls
Server side comments
Server side include directives

To explain the above elements let us take an example given below:

Example5:Message.aspx

<%@ Page Language="VB" %>

lblMessage.Text="Hello " + txtMessage.Text

End Sub

</script>

<html>

<body>

<% Response.Write("This is ASP.NET Page")%><p>

</font>

<form runat="server">

enter Your Name:

<asp:textbox id="txtMessage" runat="server"/><p>

<asp:button id="btSubmit" OnClick="Message_Change"

text="Submit" runat="server"/><p>

<b>

<asp:label id="lblMessage" runat="server"/>

</b>

<%--

this is inside the comments

<asp:label text="hello" runat="server"/>

<%= strSomeText %>

--%>

</form>

</body>

</html>

Save this page in your root directory and view it on the browser, the output is shown below. Enter your name in the textbox and click the submit button. You will see a nice hello message.

Common elements of an ASP.NET page.

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