Drupal hook_page_alter() example

Frypan Module Explained

Thanks to Pasada Media's generous offer of a free beer for anyone demonstrating a live Drupal 7 site at the Toronto D7 Release Party, I decided to upgrade this site. Now I get to play with the new toys in D7!

After a few of those free beers Andre, one of the DUG-TO crew, received a text from a friend asking about the "Frypan party". As every Drupalista with an iPhone has discovered, "Drupal" is autocorrected to "frypan". Thanks to jovial atmosphere, the Drupal-love and some bad judgement, it was suggested writing a novelty module which would autocorrect all instances of "Drupal" on a page to "Frypan".

How to do this translation? Why not try out the new API hook: hook_page_alter().

About hook_page_alter()
What hook_page_alter() does is give you the entire page in a giant nested array.

<?php
  $page['page_top']
  $page['header']
  $page['sidebar_first']
  $page['content']
  $page['sidebar_second']
  $page['page_bottom']
?>

You may then add to, remove or otherwise morph the contents of the page. The single argument $page is an array that is passed by reference, so just make all the changes you want... no return value necessary.

Sample Module

The full module code is on Github (http://github.com/cleaver/Frypan), but here's most of it:

<?php
function frypan_page_alter(&$page) {
  frypan_autocorrect($page);
}

function frypan_autocorrect(&$val) {
  if (is_array($val)) {
    foreach ($val as &$elem) {
      frypan_autocorrect($elem);
    }
  }
  elseif (is_string($val)) {
    $val = str_replace(array('Drupal', 'drupal'), array('Frypan', 'frypan'), $val);
  }
}
?>

First, the frypan_page_alter() function implements the hook. All it does is call another function that does the autocorrection.

Next, the frypan_autocorrect function recurses the array and substitutes "Frypan" for each instance of "Drupal". Note that while you can do a replace on an entire nested array in PHP, but this did not work in this case. The replace function changed all types in the nested array to string. I had to put the "is_string()" check so that the replace would only operate on string elements.

Thanks to the DUG-TO group for the event, the booze and the silly idea.