Convertig excel base64 to downloadable file PHP - php

Question

everybody, im running in some issue right now, see for internal situations with the server that i cant control or anything right now i cant use base64 encoded files directly over the website cause when the server delivers content to the browser it has a limit of characters for those tasks and it directly affects base64 encoded files cause of the lenght of those strings, so i made for one system a php script that delivers an already existing base64 pdf files to the client as a downloadable file, and it worked just like this:
$reg = File::find($args->string('id')); //querying the file from database
$filename = $reg->filename; //the original file name
$base64 = $reg->file; //the base64 encoded file
$meta_type = explode(',', $base64) [0]; //getting the meta type of the file
$meta_type = str_replace('data:', '', $meta_type);
$meta_type = str_replace(';base64', '', $meta_type);
$file = explode(',', $base64) [1];
$file = base64_decode($base64); //decoding the base64 string
header('Content-Description: File Transfer');
header('Content-Type: ' . $meta_type);
header('Content-Disposition: attachment; filename="' . $filename . '"');
header('Expires: 0');
header('Cache-Control: must-revalidate');
header('Pragma: public');
header('Content-Length: ' . (strlen($file)));
echo $file;
this worked just fine when i use pdf files but when i try to use it on some 'xlsx' files it seem to work, it download the file, the filesize and all seem to match the original, but excel cant open the file, does anybody have an idea of what im i missing here?? :)

Answer 1

I am pretty sure, its happening, because you are not exiting your function and it continues to fill up buffers. You have to stop the script immediatelly after your stream is ready, clean the buffer and exit.
If its a valid Excel file, all you have to do is:
header('Content-Type: application/vnd.openxmlformats-officedocument.spreadsheetml.sheet');
header('Cache-Control: must-revalidate');
header('Expires: 0');
header('Pragma: public');
header('Content-Disposition: attachment; filename="' . $filename . '"');
if (ob_get_contents() || ob_get_length()) {
ob_end_clean(); //or ob_end_flush();
}
exit();