Controllers\Api\Exports::showCsv PHP Method

    public function showCsv($id)
    {
        // should top timeouts on long queries
        set_time_limit(0);
        $opts = $this->getOptions();
        $model = $this->repo->show($id, $opts);
        return IlluminateResponse::stream(function () use($model, $opts) {
            if (ob_get_level() == 0) {
                ob_start();
            }
            // Outputs the field names (column headers).
            echo implode(',', array_map(function ($field) {
                return $field['to'];
            }, $model->fields)) . "\n";
            // Outputs the statements (rows).
            $this->repo->export($model, array_merge($opts, ['next' => function () {
                echo "\n";
                flush();
                ob_flush();
            }, 'stream' => function ($obj) {
                // Outputs the field values (column values).
                echo implode(',', array_map(function ($value) {
                    return $this->quoteCSV($value);
                    flush();
                    ob_flush();
                }, $obj));
            }]));
        }, 200, ['Content-Type' => 'text/csv']);
    }