Creating Hidden Controls | Spring Into PHP 5

Another handy control type in PHP is the hidden control, which lets you store hidden text data in web pages. This is useful when you want to store data about a user and the user doesn't allow cookies to be stored, for instance.

Here's an example, phphidden.html, Example 5-11, which contains the text "No worries." in a hidden control named "Hidden".

Example 5-11. Creating hidden data, phphidden.html

 <HTML>     <HEAD>         <TITLE>             Using Hidden Controls         </TITLE>     </HEAD>     <BODY>         <CENTER>             <H1>                 Using Hidden Controls             </H1>             <FORM METHOD="POST" ACTION="phphidden.php">                 Click the button to see the hidden data.                 <INPUT NAME="Hidden" TYPE="HIDDEN" VALUE="No worries.">                 <BR>                 <BR>                 <INPUT TYPE="SUBMIT" VALUE="Click Me">             </FORM>         </CENTER>     </BODY> </HTML>

You can see this page, phphidden.html, in Figure 5-11. The data in the hidden control isn't visibleobviouslybut when you click the button, the PHP script phphidden.php will retrieve that data and display it.

Figure 5-11. Using hidden controls.

You can retrieve the data from a hidden control as you'd expectby name, using $_GET or $_POST as appropriate, or by using $_REQUEST. You can see how that works in phphidden.php, Example 5-12, where we're recovering the data in the hidden control as $_REQUEST["Hidden"].

Example 5-12. Retrieving data from hidden controls, phphidden.php

 <HTML>     <HEAD>         <TITLE>             Retrieving Hidden Data         </TITLE>     </HEAD>     <BODY>         <CENTER>             <H1>Retrieving Hidden Data</H1>             The hidden data was:             <BR>             <?php                 echo $_REQUEST["Hidden"];             ?>         </CENTER>     </BODY> </HTML>

The results appear in Figure 5-12, where we've been able to read the data from the hidden control and echo it in a web page.

Figure 5-12. Reading data from hidden controls.