This simple library provides an easy way to extract a given property from an array of objects.

array extract_property( array $objects, mixed $key [, mixed $index] )

Given an array of objects, extract_property() returns the values from a single property of each object, identified by $key. Optionally, you may provide an $index to index the values in the returned array by the values from the $index property of each object in the input array.

For example, using the following $users array, we tell extract_property() to return an array of just the names, indexed by their record IDs.

<?php
$users = array();

$a = new stdClass;
$b = new stdClass;
$c = new stdClass;

$a->id = 1;
$a->name = 'John';
$a->surname = 'Doe';

$users[] = $a;

$b->id = 2;
$b->name = 'Jane';
$b->surname = 'Doe';

$users[] = $b;

$c->id = 3;
$c->name = 'Foo';
$c->surname = 'Bar';

$users[] = $c;

$names = extract_property($users, 'name', 'id');

If we call print_r() on $names, you'll see a resulting array that looks a bit like this:

Array
(
    [1] => John
    [2] => Jane
    [3] => Foo
)

You could of course omit the $index so the resulting array looks like this:

Array
(
    [0] => John
    [1] => Jane
    [2] => Foo
)

The easiest way to install this library is to use Composer and add the following to your project's composer.json file:

{
    "require": {
        "dcelasun/extract_property": "1.*"
    }
}

Then, when you run composer install, everything will fall magically into place, and the extract_property() function will be available to your project, as long as you are including Composer's autoloader.

However, you do not need Composer to use this library.

This library has no dependencies and should work on older versions of PHP. Download the code and include src/extract_property.php in your project, and everything should work fine.