How Can I Sort a PHP Array Based on a Predefined Key Order?

Customizing Array Sorting Using a Reference Array

In PHP, arrays can be sorted in various ways, but it can be challenging to sort them in a specific order based on a different array. This article provides a solution to this issue, explaining how to sort a flat associative array based on a predefined key order.

The proposed solution leverages the array_merge or array_replace functions. These functions take two arrays as arguments: the first one specifies the desired order (in the form of key-value pairs), and the second one contains the actual data to be sorted.

Here's how these functions work:

array_merge: It merges the two arrays by starting with the order array and overwriting or adding keys with data from the actual array.

array_replace: It does the same as array_merge but only overwrites existing keys.

Consider the following example:

$customer['address'] = '123 fake st';
$customer['name'] = 'Tim';
$customer['dob'] = '12/08/1986';
$customer['dontSortMe'] = 'this value doesnt need to be sorted';

$properOrderedArray = array_merge(array_flip(array('name', 'dob', 'address')), $customer);

In this example, array_flip creates an array where the elements ('name', 'dob', 'address') become keys and the keys become values. This acts as the order array. By merging this order array with $customer, the $properOrderedArray is generated with the desired key order while preserving the actual data.

The resulting $properOrderedArray would be:

array(
  'name'       => 'Tim',
  'dob'        => '12/08/1986',
  'address'    => '123 fake st',
  'dontSortMe' => 'this value doesnt need to be sorted')

This approach allows for flexible sorting of flat associative arrays based on any predefined order array, ensuring the correct ordering of keys and their corresponding values.

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