Jack Born On Marketing, Online Business, and PHP Code

I recently saw a post in the forums for WordPress where someone was trying to add someone else’s php code to their themes. The code started off by setting a cookie. It was correctly commented in the source code to

…put this before any html

The reason being that to set a cookie, there must be no information sent to the browser yet. This is also true of other header(); php commands.

So, how can we put the script where we want, without having a whole bunch of errors thrown on the page?

The easiest (and most elegant) solution is to use php’s built in output buffering. Using output buffering means that memory is allocated for the output of the code and isn’t sent to the browser until you specifically tell it to do so.

The beautiful outcome is that you can get away with putting things in the ‘wrong’ order and get away with it.

For example, normally this code would break horribly:

<?php
echo 'Some text here';
header('Location: http://www.yahoo.com/');
?>

You’d get an error saying “headers already sent”

But the same code with output buffering works like a charm.

<?php
ob_start();
echo 'Some text here';
header('Location: http://www.yahoo.com/');
$contentStuff = ob_get_contents();
ob_end_clean();
echo $contentStuff;
?>

Now let’s apply this concept to themes as they are currently written for WordPress 1.5.1.2

No need to find a new theme, just open up index.php or possibly page.php

You’ll likely find code like this:

<?php get_header(); ?>
(the rest of the php code here)
<?php get_footer(); ?>

All you need to do is change it to


<?php
ob_start();
get_header(); ?>
(the rest of the php code here)
<?php get_footer();
$contentStuff = ob_get_contents();
ob_end_clean();
echo $contentStuff;
?>

So long as ob_start() is called before any output is sent the browser, adding php code to the sidebar, or any other part of your theme, shouldn’t cause any problems with headers.

Update: I just updated the Static Jack plugin to have output buffering enabled. So, even though you understand how to do this to your templates with hardcoding, you’ve now got the option to use output buffering instantly on ALL of your templates with the click of a button.

Enjoy.

This entry was posted on Sunday, June 5th, 2005 at 3:25 pm and is filed under Programming, WordPress . You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.