Force File Download in PHP

The previous lesson of PHP Lessons Series was about selecting data from mysql database in php and in this lesson we will learn to force a file download in php using readfile() function and CURL separately.

PHP file download using readfile() function:

Let us say we have a text link (Download File) and we want to download a png image when someone clicks on the link. Consider the text link given below:

<a href="download.php?download_file_name=image.png">Download File</a>

An easy way to force the image download when someone clicks on the above link is by redirecting the user to download.php file and pass the parameter download_file_name in the url. The php code of the file (download.php) will do the rest to download the image with the file name passed in the url.

PHP file download.php

<?php
if(isset($_GET['download_file_name'])){

 $file = $_GET['download_file_name'];   // get the file name
 $file = str_replace(" ","%20",$file);  // replace the spaces in the file name with %20
 if(file_exists($file)){
  header('Content-Description: File Transfer');
  header('Content-Type: application/octet-stream');
  header('Content-Disposition: attachment; filename='.basename($file));
  header('Expires: 0');
  header('Cache-Control: must-revalidate');
  header('Pragma: public');
  header('Content-Length: '.filesize($file));
  readfile($file);
  exit;
 }
} 
?>

The above php code will download image.png file.

PHP file download using CURL:

Just like in the case of readfile() function, we will use the text image link to download the image i.e

<a href="download.php?download_file_name=image.png">Download File</a>

The link will remain the same, we need to change the php code inside the file (download.php). The PHP code of file download using CURL is given below:

PHP file download.php

<?php
if(isset($_GET['download_file_name'])){
 $file = $_GET['download_file_name'];
 $file = str_replace(" ","%20",$file);
 if(file_exists($file)){
  set_time_limit(0);
                // create and open a temp png file to save the downloaded file
  $fileopen = fopen ('tmp.png', 'w+');   
  if($fileopen){
   $ch = curl_init($file); 
   curl_setopt($ch, CURLOPT_URL, $file);
   curl_setopt($ch, CURLOPT_FILE, $fileopen);
   curl_setopt($ch, CURLOPT_HEADER, 0);
   curl_setopt($ch, CURLOPT_TIMEOUT, 50);  // set time out
   $data = curl_exec($ch);   // curl execute
   if ($data === FALSE) {   // if curl execution fails
                                // show the curl execution error
    die("Curl failed: " . curL_error($ch));   
   }
   curl_close($ch);
   fclose($fileopen);

  }else{
   echo 'File is not opened';
  }
  
 } 
}
?>

The above php code will copy the file image.png from some other server to tmp.png created on your server.

Stay tuned for more lessons...