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<?php $array = [ [ 'id' => 1, 'parentId' => "" ], [ 'id' => 2, 'parentId' => 1 ], [ 'id' => 3, 'parentId' => 2 ] ]; $entriesById = array_column($array, null, 'id'); $entriesWithAncestors = array_reduce( $entriesById, static function (array $result, array $entry) use ($entriesById): array { $result[$entry['id']] = $entry + ['ancestors' => []]; $parentId = $entry['parentId']; while (isset($result[$parentId])) { $result[$entry['id']]['ancestors'][] = $result[$parentId]; $parentId = $entriesById[$parentId]['parentId'] ?? null; } return $result; }, [] ); print_r($entriesWithAncestors);
Output for 7.2.0 - 7.2.33, 7.3.0 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.28, 8.2.0 - 8.2.19, 8.3.0 - 8.3.4, 8.3.6 - 8.3.7
Array ( [1] => Array ( [id] => 1 [parentId] => [ancestors] => Array ( ) ) [2] => Array ( [id] => 2 [parentId] => 1 [ancestors] => Array ( [0] => Array ( [id] => 1 [parentId] => [ancestors] => Array ( ) ) ) ) [3] => Array ( [id] => 3 [parentId] => 2 [ancestors] => Array ( [0] => Array ( [id] => 2 [parentId] => 1 [ancestors] => Array ( [0] => Array ( [id] => 1 [parentId] => [ancestors] => Array ( ) ) ) ) [1] => Array ( [id] => 1 [parentId] => [ancestors] => Array ( ) ) ) ) )
Output for 8.3.5
Warning: PHP Startup: Unable to load dynamic library 'sodium.so' (tried: /usr/lib/php/8.3.5/modules/sodium.so (libsodium.so.23: cannot open shared object file: No such file or directory), /usr/lib/php/8.3.5/modules/sodium.so.so (/usr/lib/php/8.3.5/modules/sodium.so.so: cannot open shared object file: No such file or directory)) in Unknown on line 0 Array ( [1] => Array ( [id] => 1 [parentId] => [ancestors] => Array ( ) ) [2] => Array ( [id] => 2 [parentId] => 1 [ancestors] => Array ( [0] => Array ( [id] => 1 [parentId] => [ancestors] => Array ( ) ) ) ) [3] => Array ( [id] => 3 [parentId] => 2 [ancestors] => Array ( [0] => Array ( [id] => 2 [parentId] => 1 [ancestors] => Array ( [0] => Array ( [id] => 1 [parentId] => [ancestors] => Array ( ) ) ) ) [1] => Array ( [id] => 1 [parentId] => [ancestors] => Array ( ) ) ) ) )

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