What is the best way to store files for requests?

Question

PHP

The user can create new applications in the system and attach files to them.
What is the best way to implement file storage.
1) All in the same folder, but do operations on the name.
2) Each application has its own folder (application id its name)
3) Either folders by dates and already switch to names
The best option I think is 2. But there are user problems, the folder needs to be created as soon as the user enters the application page. If he closed it, delete the folder and record in the database. Or first upload the files to a temporary folder, and then transfer them to the application folder?

Answer 1

Why create a directory before it's needed? Can't you just create a directory if $_FILES is not empty?
In the php doc, see move_uploaded_file