I implement this functionality using this1 instruction but I don't know how to compare generated file name with uploaded files.
Edit:
I generate new file name using this code:
/**
* Called before saving the entity
*
* @ORM\PrePersist()
* @ORM\PreUpdate()
*/
public function preUpload()
{
if (null !== $this->file) {
// do whatever you want to generate a unique name
$filename = sha1(uniqid(mt_rand(), true));
$this->path = $filename.'.'.$this->file->guessExtension();
}
}