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<?php $array = [ ['_id' => '5f76b1788ee23077dccd1a2c', 'product' => ['_id'=>'5d0391a4a72ffe76b8fcc610'], 'count'=> 1], ['_id' => '5f76b6288ee2300700cd1a3a', 'product' => ['_id'=>'5d0391b6a72ffe76b8fcc611'], 'count'=> 1], ['_id' => '5f76d2488ee23083d3cd1a4a', 'product' => ['_id'=>'5d0391b6a72ffe76b8fcc611'], 'count'=> 1] ]; $result = []; foreach ($array as $item) { $productId = $item['product']['_id']; if (!isset($result[$productId])) { $result[$productId] = $item; } else { $result[$productId]['count'] += $item['count']; } } var_export(array_values($result));
Output for 7.2.0 - 7.2.34, 7.3.0 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.33, 8.2.0 - 8.2.29, 8.3.0 - 8.3.25, 8.4.1 - 8.4.12
array ( 0 => array ( '_id' => '5f76b1788ee23077dccd1a2c', 'product' => array ( '_id' => '5d0391a4a72ffe76b8fcc610', ), 'count' => 1, ), 1 => array ( '_id' => '5f76b6288ee2300700cd1a3a', 'product' => array ( '_id' => '5d0391b6a72ffe76b8fcc611', ), 'count' => 2, ), )

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