PHP Spreadsheet: After saving data to a new worksheet, the data of the previous worksheets are deleted - phpspreadsheet

Question

I am creating a script to save CSV data into an excel document, but in different worksheets, I mean, every CSV doc will go into a new worksheet, but after saving data to a new worksheet the previous data that are in the other worksheets are deleted. This is my code
<?php
require 'vendor/autoload.php';
use PhpOffice\PhpSpreadsheet\Spreadsheet;
use PhpOffice\PhpSpreadsheet\Writer\Xlsx;
$spreadsheet = new Spreadsheet();
$spreadsheet2 = new Spreadsheet();
$reader = new PhpOffice\PhpSpreadsheet\Reader\Xlsx();
$spreadsheet = $reader->load('test.xlsx');
$numSheets = $spreadsheet -> getSheetCount();
$reader2 = new PhpOffice\PhpSpreadsheet\Reader\Csv();
/* Set CSV parsing options */
$reader2->setDelimiter(',');
$reader2->setEnclosure('"');
$reader2->setSheetIndex($numSheets);
echo $numSheets;
/* Load a CSV file and save as a XLS */
$spreadsheet2 = $reader2->load('testcsv.csv');
$writer = new Xlsx($spreadsheet2);
$writer->save('test.xlsx');
$spreadsheet->disconnectWorksheets();
unset($spreadsheet);
?>
With this only the last worksheet have data
enter image description here
I want to emphasize that I have no errors but I am not achieving what I want to do

Answer 1

The problem is that you use
$numSheets = $spreadsheet -> getSheetCount();
but you must count your sheet numbers and add a new sheet in your file.
I would suggest you use a loop.
$numSheets = $spreadsheet -> getSheetCount();
foreach($csvs as $csv){
// Create a new worksheet called "My Data"
$myWorkSheet = new \PhpOffice\PhpSpreadsheet\Worksheet\Worksheet($spreadsheet, 'My Data');
// Attach the "My Data" worksheet as the first worksheet in the Spreadsheet object
$spreadsheet->addSheet($myWorkSheet, $numSheets);
$numSheets++;
}
More information here