How to store files temporarily using Laravel? - php

Question

Using Laravel 5.2, I am working on an upload form which should allow the user to select up to 10 images, display their previews and then let him sort them arround, add more images or remove the ones he doesn't want to upload.
The sorting and removal of previews can quite easily be done using javascript but beyond that I am having a hard time figuring out how to properly do the rest. My original idea was to get the js file array from the input, move it to another array and work with that once the user interacts with the image previews, which would be displayed using FileReader.
Once he submits the form I would create a FormData object, remove the current files in input and add all the valid ones:
var formdata = new FormData(document.getElementById('upload-form'));
if (formdata.has('pic[]') && validFiles.length) {
formdata.delete("pic[]");
var len = validFiles.length;
for (i = 0; i < len; i++) {
formdata.append("pic[]", validFiles[i]);
}
}
If you know your way around js you can already see that this approach has severe problems when it comes to backwards compatibillity, as the FormData.delete(..), .append(..) and .has(..) methods are not supported by older browsers (including Chrome 50 and below or pretty much any IE.)
Ok scrap that idea. My second idea was to do the following:
User selects images to add
Upload said images using ajax and store them temporarily somewhere using Laravel
Return image previews
Let the user use the previews to reorder the files or remove them and keep track of what he does.
Once the form is submitted take all the other info, figure out which files are to be stored forever and which ones to delete and save.
Now I am not quite sure how to do this. I was thinking that I coud have a tmp directory for these images, generate some sort of a string to be the name of the directory associated with the users session, store the files there and save the directory name using Session.
The problem with this is that Session seems to have a global timeout and cannot be set to expire in say 15 minutes. Another problem I see is that once the Session expires and the user decides to not upload the images they would stay on the server forever as I couldn't find a method that would allow me to execute code upon Session expiry.
So what is the proper way to do temporary file storage in Laravel?
Or am going in the wrong direction here and can you see a better way to do what I am attempting to do?
Thanks in advance for any advice.

Answer 1

Your second idea seems to be the way to go, but slightly modified.
How about this:
<?php
// Collect a list of files in a $tempLocation (modify this to your usage)
collect(\File::files($tempLocation))->map(function($file) {
return [
'file' => $file,
'basename' => pathinfo($file)['filename']
];
// Filter out the non-numeric files and those that are before now
})->filter(function($a) {
return is_numeric($a['basename']) && $a['basename'] < time();
// Delete each file that is outdated
})->each(function($file) {
try { unlink($file['file']); } catch($e) { /* Fill me in */ }
});
Your usual workflow would then be to upload your users' files with the nomenclature:
{timestamp + timeout}.{ext}
You'd then put the above function in a daily or weekly cron. All the "old" files would be deleted. If your user wants to keep a file simply move the file elsewhere, in a non-temporary directory, or rename it to something non-numeric.
This also means the frontend won't need to take care of deleting the files or notifying your backend that they need to be discarded.
I hope this helps.