php $_REQUEST['id'] returns error

Question

So I was working on php navigation using index.php?id=MYID. I used some random website to learn the code. and it is here

I made my program worked successfully, I mean that it is navigating users to other pages successfully. But it is showing some kind of error. which is

Notice: Undefined index: id in C:\xampp\htdocs\php_tests\index.php on line 17

I tried everything out. It is my first question here so I may not be able to clear my self so I also request my mentors to guide me if there is anything wrong in my question and also answer my question. My code is below:

<table width="125" cellpadding="0" cellspacing="0" style="display:inline;">
   <tr>
      <td><a href="index.php?id=main" target="_self" name="main">Home</a></td>
   </tr>
   <tr>
      <td><a href="index.php?id=News" target="_self" name="news">News</a></td>
   </tr>
   <tr>
      <td><a href="index.php?id=MoreInfo" target="_self" name="MoreInfo">MoreInfo</a></td>
   </tr>
</table>
<div id="section" style="height:500px; width=:auto; background-color:#CCC">
   <?php
      $id = $_REQUEST['id']; // this will get the id of the link, this will be explained later.

      switch($id) { // make a case with the id
      default: include('main.php'); //When page is loaded this will be the main content, put the content in main.php(you can change the name)
      break; // close this case

      case "News": include('news.php'); // The content in news.php will be called when id=News
      break; // close this case

      case "MoreInfo": include('MoreInfo.php'); // The content in MoreInfo.php will be called when id=Members
      break; // close this case


      } // close switch
      ?>
</div>

This is basic concept, you should learn before starting coding. — Milap, Feb 02 '16 at 09:18
is user getting redirected to other page after selecting ID ? — Dr Manish Lataa-Manohar Joshi, Feb 02 '16 at 09:27
Yes he is. But the problem is, that it shows error when index.php is accessed, index.php uses content from main.php by default and it is also showing content successfully, but then again, whats the error about. — Mohammad Abbas, Feb 02 '16 at 09:30

devpro · Accepted Answer · 2016-02-02T09:20:30.357

0

You need to check if value is set or not like:

<?php
$id = ''; // define as empty in default
if(isset($_REQUEST['id'])){
    $id = $_REQUEST['id'];
}
?>

Also keep in mind, if you not set $id as empty in default than you will again get undefined variable notice for $id.

From PHP Manual:

isset — Determine if a variable is set and is not NULL

edited Feb 02 '16 at 09:20

answered Feb 02 '16 at 09:14

devpro

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Ok...I a added a code to check if variable is set or not. It checks successfully but this time, it vanishes my main.php content which is to be loaded on default index.php. – Mohammad Abbas Feb 02 '16 at 09:28
@MohammadAbbas: abbas, when u use MYID it will include the main.php file only that u defined in default. – devpro Feb 02 '16 at 09:43

php $_REQUEST['id'] returns error

1 Answers1