Using header() to redirect after using include()

Question

I have a page structured like below and I am having issues getting the redirect to work. This page gets an ID from the URL and uses it in the query. If there isn't a match, just redirect to another page.

I am getting the "headers already sent error," due to the include. I need the include to be there regardless. Is there a different way I can do the redirect if the query result is empty?

include('somepage.php');

$id = $_GET['id'];
$query = mysql_query("My query is here");

if(mysql_num_rows($query)==0) { header('Location:htp://example.com'); }

I've tried using exit(); and the various stop processing functions.

somepage.php:

<html>
<head>
(standard html)
include('sql-connect.php');
</head>

<body>
(code to format the header portion of the site)

Why does the include have to be there? Are you outputting HTML in somepage.php? — codeaddict, Feb 02 '14 at 18:05
what does somepage do - it is obviously outputting something - avoid it doing that and you should be able to redirect — Shaun Hare, Feb 02 '14 at 18:05
pleae show us the somepage.php too. I there is an output before the header, it wont work. — toesslab, Feb 02 '14 at 18:06

score 2 · Accepted Answer · edited Mar 19 '19 at 10:03

2

You can put ob_start() at the beginning of the file, so that it looks like this:

<?php
ob_start();
include 'somepage.php';

$id = $_GET['id'];
$query = mysql_query("My query is here");

if(mysql_num_rows($query)==0) { header('Location:http://example.com'); }

Also, you can echo html redirect:

<?php
if(mysql_num_rows($query)==0) { echo '<meta http-equiv="refresh" content="0; url=http://example.com/">'; die(); }

edited Mar 19 '19 at 10:03

ThePierrasse

15
5

answered Feb 02 '14 at 18:08

Martin Janeček

560
4
20

THANK YOU! So simple. I can accept your answer in about 10 minutes. – Matt. Feb 02 '14 at 18:09
I used only ob_start(); – Matt. Feb 02 '14 at 18:15
1

In free time, read about that in http://stackoverflow.com/questions/8028957/how-to-fix-headers-already-sent-error-in-php as @Hamza mentioned – Martin Janeček Feb 02 '14 at 18:17

score 1 · Answer 2 · edited May 28 '18 at 10:20

1

You need to add ob_start() at the beginning of the file and if this still does not work then you also need to add ob_flush(); to fully flush out the old header.

    flush(); // Flush the buffer
    ob_flush();
    header("Location: http://example.com");

edited May 28 '18 at 10:20

ThePierrasse

15
5

answered Feb 02 '14 at 18:10

Hamza

1,593
2
19
31

Thanks! That is correct, same as Martin said before you. – Matt. Feb 02 '14 at 18:11
2

Just as a knowledge, read the answer by Mario at http://stackoverflow.com/questions/8028957/how-to-fix-headers-already-sent-error-in-php – Hamza Feb 02 '14 at 18:13

score 0 · Answer 3 · answered Feb 02 '14 at 18:11

You may have a blank line after a closing ?> This will cause some literal whitespace to be sent as output, preventing you from making subsequent header calls. Note that it is legal to leave the close ?> off the include file, which is a useful idiom for avoiding this problem.

ob_start() may fix your problem.

<html>
<?php
/* This will give an error. Note the output
 * above, which is before the header() call */
header('Location: http://www.example.com/');
exit;
?>

score 0 · Answer 4 · edited Mar 19 '19 at 08:57

"headers already sent error" means that your script (somepage.php) already sent headers to the browser, so you can't change these headers and redirect user to the other URL.

The best solution is to move the "include" operator after your check:

$id = $_GET['id'];
$query = mysql_query("My query is here");

if(mysql_num_rows($query)==0) { header('Location:http://example.com'); }

include('somepage.php');

Also, you can prevent your somepage.php from sending any data to the client.

The second variant is to use the functions ob_start(), ob_get_contents(), ob_end_clean():

ob_start();
include('somepage.php');

$id = $_GET['id'];
$query = mysql_query("My query is here");

if(mysql_num_rows($query)==0) { header('Location:http://example.com'); }
$content = ob_get_contents():
ob_end_clean();
echo $content;

Using header() to redirect after using include()

4 Answers4