As a Drupal developer, I spend 90% of my time mucking with PHP arrays. And as much as I love a foreach control structure, PHP provides some nice functions that can get you what you need from an array without having to loop through a huge Drupal Node array.

For example, say I wanted to filter some nodes to see if they were referencing a specific Vocabulary term: The array_filter function can be used to filter out empty values from an array, but it can also be used with a callback function to filter based on whatever specification you want:

Here's the simple "Filter out empty values" behavior:

<?php
$array = array(
1 => 'Apple',
2 => NULL,
3 => 1,
);
$filtered_array = array_filter($array);
print_r($filtered_array);
// Returns: Array ( [1] => Apple [3] => 1 )
?>

But what if we wanted to filter for anything with a specific value?

<?php
function apple_callback($item) {
if($item == 'Apple') {
return TRUE;
}
return FALSE;
}
$callback_filtered_array = array_filter($array, 'apple_callback');
print_r($callback_filtered_array);
// Returns: Array ( [1] => Apple )
?>

Dynamically filtering with a closure

As of PHP 5.3, the callback function can also be a "closure", or anonymous function. This allows for dynamically setting the value for the filter, which is awesome:

<?php
function filter_closure($filter_value) {
return function($item) use($filter_value) {
return $item == $filter_value;
};
}

$dynamic_variable = 'Apple';$anonymous_filter = filter_closure($dynamic_variable);$array_filtered_closure = array_filter($array, $anonymous_filter);print_r($array_filtered_closure);// Returns: Array ( [1] => Apple )

?>