How to check if user uploaded a file in PHP?

Question

I do some form validation to ensure that the file a user uploaded is of the right type. But the upload is optional, so i want to skip the validation if he didn't upload anything and submitted the rest of the form. How can I check if he uploaded something or not? Will $_FILES['myflie']['size'] <=0 work?

Answer 1

You can use is_uploaded_file():

if(!file_exists($_FILES['myflie]['tmp_name']) || !is_uploaded_file($_FILES['myflie']['tmp_name'])) {
    echo 'No upload';
}

From the docs:

Returns TRUE if the file named by filename was uploaded via HTTP POST. This is useful to help ensure that a malicious user hasn't tried to trick the script into working on files upon which it should not be working--for instance, /etc/passwd.

This sort of check is especially important if there is any chance that anything done with uploaded files could reveal their contents to the user, or even to other users on the same system.

EDIT: I'm using this in my FileUpload class, in case it helps:

 public function fileUploaded()
        {
  if(empty($_FILES)) {
   return false;  
  } 
  $this->file = $_FILES[$this->formField];
  if(!file_exists($this->file['tmp_name']) || !is_uploaded_file($this->file['tmp_name'])){
   $this->errors['FileNotExists'] = true;
   return false;
  } 
  return true;
 }