Uploading files is easy. But if we have the file already uploaded in the system, we can want

• only display it (preferably with a preview),
• or delete the file,
• or replace the file with another version.

A somewhat inconvenient situation is when we get some unrelated error elsewhere in the form. So we return the form for the user to correct it. But the uploaded file or files must be restarted. We solve this with a transaction. Once uploaded, the file is stored in a special storage (by default it is handled as a tempo directory, it can be changed), and entered into the system after successfully saving the form.

We represent image files as images. If the standard renderer is not suitable, we can set our own.

The input value can have three options:

• Null: none, or original file deleted
• FileUploaded: new file uploaded
• FileCurrent: the original file stored in the system

composer require tacoberu/nette-form-fileupload

use Taco\Nette\Forms\Controls\FileCurrent;
use Taco\Nette\Forms\Controls\FileControl;
use Taco\Nette\Forms\Controls\GenericFilePreviewer;

$form = new Nette\Forms\Form;

$form['portrait'] = (new FileControl('Portrait:'))
	->setDefaultValue(new FileCurrent("uploaded/account/56695/mp16.jpg", "image/jpeg"))
	->setPreviewer(new GenericFilePreviewer());

When the file is successfully uploaded to the server, it is automatically moved to the storage, transaction. This will serve to if the form is not processed, but is, for example, passed back to the user for validation reasons, it is not necessary to upload the file again. After successful processing, the file is available using $control->getValue() like the other values.

After the file is uploaded to the system, the transaction can be discarded. Well, in case using the default storage UploadStoreTemp, delete the directory. We can either do this explicitly:

$form['portrait']->destroyStore();

Or leave it to the GC, which will delete it automatically after a certain period of time.

Automatic greasing is implemented in UploadStoreTemp. it acts like that after the page exits, all relevant transactions are passed through the destructor and checks if the transaction is older than UploadStoreTemp::$gcAgeLimit. This only deletes UploadStoreTemp::$gcMaxCount transactions/directories to spread the load.

This behavior is only a matter of the UploadStoreTemp implementation.