msort.php

<?php

/**
 * Get value at a given path expressed in dot notation.
 *
 * @param array $arr
 * @param string $path
 * @return mixed
 */
function array_dot_notation(array $arr, string $path)
{
    $path = array_map(function($i) {
        return trim($i);
    }, explode('.', $path));

    foreach ($path as $p) {
        if (! isset($arr[$p])) {
            return null;
        } else {
            $arr = $arr[$p];
        }
    }

    return $arr;
}

/**
 * Sort multi-dimensional array using multiple predicates.
 * 
 * @param array $data
 * @param array $predicates
 * @return array
 */
function msort(array $data, array $predicates): array
{
    $predicatesArr = [];

    foreach ($predicates as $predicate => $order) {
        $predicatesArr[$predicate] = [];

        foreach ($data as $i => $row) {
            if (strstr($predicate, '.') !== false) {
                $valueAtPath = array_dot_notation($row, $predicate);
            } else {
                $valueAtPath = $row[$predicate] ?: null;
            }

            $predicatesArr[$predicate]['_' . $i] = strtolower($valueAtPath);
        }

        if (! count($predicatesArr[$predicate])) {
            unset($predicatesArr[$predicate]);
            unset($predicates[$predicate]);
        }
    }

    if (empty($predicatesArr)) {
        return $data;
    }

    $eval = 'array_multisort(';
    foreach ($predicates as $predicate => $order) {
        $eval .= '$predicatesArr[\'' . $predicate . '\'],' . $order . ',';
    }

    $eval = substr($eval, 0, -1) . ');';
    eval($eval);

    $output = [];
    foreach ($predicatesArr as $predicate => $predicateArr) {
        foreach ($predicateArr as $i => $v) {
            $i = substr($i, 1);
            if (! isset($output[$i]))
                $output[$i] = $data[$i];
        }
    }

    return $output;
}

A simple solution to sort multi-dimensional array using multiple sort criteria/properties, which may be in the form of dot notation. The direction of sort can also be defined per criterion/property.

Sample usage:

$data = [
    [
        "id"        => 1,
        "product"   => "iPhone X",
        "price"     => [
            "retail"    => 699.99,
            "sale"      => 599.99
        ]
    ],
    [
        "id"        => 2,
        "product"   => "Google Pixel 3",
        "price"     => [
            "retail"    => 799.99,
            "sale"      => 399.99
        ]
    ],
    [
        "id"        => 3,
        "product"   => "Samsung Galaxy Note 3",
        "price"     => [
            "retail"    => 699.99,
            "sale"      => 549.99
        ]
    ],
];

$sortCriteria = [
    "price.sale"    => SORT_ASC,
    "price.retail"  => SORT_DESC,
    "product"       => SORT_ASC
];

$sorted = msort($data, $sortCriteria);