makeCsv.php

<?php
class makeCsv
{
    public function arrangeData()
    {
        try {
            //サンプルデータ
            //$_POST['data']
            $post_data = [
                ['お客様ID', '購入金額', '購入日付'],
                [1, 1200, '2021/12/08 17:15'],
                [2, 2700, '2021/12/09 11:45'],
                [3, 1500, '2021/12/09 13:35']
            ];
            //Windows向け設定
            $delimiter        = ',';
            $enclosure        = '"';
            $enclosure_escape = '""';
            $line_break       = "\r\n";
            //データをCSV用にアレンジ
            $csv = '';
            foreach($post_data as $row) {
                $values = [];
                foreach($row as $value) {
                    $values[] = $enclosure.str_replace($enclosure, $enclosure_escape, $value).$enclosure;
                }
                $csv .= implode($delimiter, $values).$line_break;
            }
            header('Content-Type: application/octet-stream');
            header('Content-disposition: attachment; filename=temp.csv');
            echo json_encode($csv);
        } catch (\Exception $e) {
            http_response_code(400);
            echo json_encode([
                'status'  => false,
                'message' => $e->getMessage()
            ]);
        }
    }
}