PDF download - use wordpress functions

Question

I'm creating a plugin where user can download files. Currently I display download links like:

<a href="plugin/directory/some/path/download.php?file_to_download_id=1">Some Download</a>

Problem:

I need to use wordpress core functionality like is_user_logged_in() or get_current_user_id() in the download.php . How am I able to use these functions in this php file?

(PS: I do not want to include wp-load in download.php)

Answer 1

You should create a function in your plugin where you listen to a specific URL or watch for specific parameters. For example to generate the download link:

<?php
    $nonce = wp_create_nonce( 'download-' . $filename );
    echo '<a href="/?_wp_nonce="' . $nonce . '&download=' . $filename . '">Some Download</a>';
?>

And to download the file:

if ( ! empty( $_GET['_wp_nonce'] ) && ! empty( $_GET['download'] ) && wp_verify_nonce( $_GET['_wp_nonce'], 'download-' . $_GET['download'] ) ) {
    /*
     * Check if file exists and then output the right headers and the content of the file
     */

    exit;
}

Answer 2

WordPress provides a couple cookies that track whether the user is logged in and what their user ID is. These are described on this page in the Codex:

After login, wordpress sets the wordpress_logged_in_[hash] cookie, which indicates when you're logged in, and who you are, for most interface use.

WordPress also sets a few wp-settings-{time}-[UID] cookies. The number on the end is your individual user ID from the users database table. This is used to customize your view of admin interface, and possibly also the main site interface.

If you absolutely must avoid loading wp-load.php in your download.php file, you could check for the existence of these cookies in your file using the $_COOKIE global and parse the wp-settings-{time}-[UID] cookie to get the user ID ("UID").

In my honest opinion, I think this is a waste compared to just including the following two lines at the top of your download.php file:

define( 'WP_USE_THEMES', false );
require( './wp-load.php' ); 

This won't load any theme files or template functions, but will instantly give you access to the core WordPress functions you are looking for. I would encourage you to try it both ways (if you are so inclined) and see the performance difference... it won't be much, especially on a server running PHP7.

Answer 3

As you have mentioned the file is located in your plugins folder you do not need to add the wp-load.php file here in case if you are not able to use the default WordPress functions. You need to include the file from your plugin's main PHP file.

Hope this solves your query.