PHP script downloads the php file itself instead of the file given - php

Question

I already asked this question, but not correctly, and I didn't know, that I can't execute a html page and start a download on the same page, but now I know. The main problem actually still remains, I can't get the CSV file to download, it always get the PHP self. The code is executed. I didn't find any information about CSV in the php.ini. I created the file directly before the download (in another page), so it's impossible, that the it doesn't exist.
<?php
if(empty($_POST['checkbox_put_it_in_CSV_too'])!=1){
$file=fopen('created_files/Rankrohad_P_2021-04-01.csv','w');
$filename='created_files/Rankrohad_P_2021-04-01.csv';
foreach($rankrohad as $line){
fputcsv($file,$line,"|","'");
}
fclose($file);
$fsize=filesize($filename);
if(file_exists($filename)){
header('Content-Description: File Transfer');
header('Content-Type: application/csv');
header('Content_Disposition: attachment; filename="'.$filename.'"');
header('Expires: 0');
header('Cache-Control: must-revalidate');
header('Pragma: no-cache');
header('Content-Length: '.$fsize);
readfile($filename);
exit;
}
}
?>

Answer 1

The problem is with your headers. Try this:
if(file_exists($filename)){
$fsize=filesize($filename);
header('Content-Description: File Transfer');
header('Content-Type: application/csv');
header("Content-Disposition: attachment; filename=\"$filename\"");
header('Expires: 0');
header('Cache-Control: must-revalidate');
header('Pragma: no-cache');
header('Content-Length: '.$fsize);
readfile($filename);
exit;
}
At Content-Disposition header I escaped the filename and I placed filesize function in IF.