How to validate file upload field?

Question

I can't seem to validate file upload fields, here's my code:

<?php

    if (isset($_POST['submit'])) {
        if ($_POST['uploadFile']) {
            echo "File uploaded";
        } else {
            echo "No file attempted to be uploaded";
        }
    }

?>

<form action="" method="post" enctype="multipart/form-data">
    <input type="file" name="uploadFile" />
    <input type="submit" name="submit" />
</form>

What is the mistake I'm making?

EDIT

Came up with my own solution, may not be the best but it works:

if (isset($_POST['submit'])) {
    $fileUpload = $_FILES['uploadFile'] ['name'];
        if (strlen($fileUpload) > 0) {
            echo "File uploaded.";
        } else {
            echo "No File attempted to be uploaded.";
        }
}

Answer 1

the superglobal your are looking for is $_FILES.

var_dump($_FILES); //to see what's happening with the uploaded files

To make sure a POST request is made you can use the following lines:

if($_SERVER['REQUEST_METHOD'] == 'POST') {
   //A post request!
}

Answer 2

As far as validation, take a look at is_uploaded_file() and read up on Handling File Uploads.

Answer 3

In this script we add some restrictions to the file upload. The user may only upload .gif or .jpeg files and the file size must be under 20 kb:

<?php
if ((($_FILES["file"]["type"] == "image/gif")  
|| ($_FILES["file"]["type"] == "image/jpeg")  
|| ($_FILES["file"]["type"] == "image/pjpeg"))  
&& ($_FILES["file"]["size"] < 20000))  
      {  
      if ($_FILES["file"]["error"] > 0)  
    {  
    echo "Error: " . $_FILES["file"]["error"] . "<br />";  
    }  
  else  
    {  
    echo "Upload: " . $_FILES["file"]["name"] . "<br />";  
    echo "Type: " . $_FILES["file"]["type"] . "<br />";  
    echo "Size: " . ($_FILES["file"]["size"] / 1024) . " Kb<br />";  
    echo "Stored in: " . $_FILES["file"]["tmp_name"];  
    }  
  }  
else  
  {  
  echo "Invalid file";  
  }  
?>  

Answer 4

In file uploads with PHP, i think $_FILES[$file]['error'] is your best friend! it breaks it down in 8 possible scenarios, 0 meaning file upload went ok, so something like hereinafter should do the trick

if($_FILES[$file]['error']==0)
// proceed
else
switch($_FILES[$file]['error'])
// debugging