Enable non-filesystem attachments with wp_mail()

wpmail-enhanced-attachments.php

<?php

/**
 * Plugin Name: Enhanced WP Mail Attachments
 * Plugin URI: https://gist.github.com/thomasfw/5df1a041fd8f9c939ef9d88d887ce023/
 * Version: 0.1
 */

/**
 * Adds support for defining attachments as data arrays in wp_mail().
 * Allows us to send string-based or binary attachments (non-filesystem)
 * and gives us more control over the attachment data.
 * 
 * @param array  $atts  Array of the `wp_mail()` arguments.
 *     - string|string[] $to          Array or comma-separated list of email addresses to send message.
 *     - string          $subject     Email subject.
 *     - string          $message     Message contents.
 *     - string|string[] $headers     Additional headers.
 *     - string|string[] $attachments Paths to files to attach.
 *
 * @see https://gist.github.com/thomasfw/5df1a041fd8f9c939ef9d88d887ce023/
 */
add_filter( 'wp_mail', function( $atts )
{
    $attachment_arrays = [];
    if ( array_key_exists('attachments', $atts) && isset($atts['attachments']) && $atts['attachments'] )
    {
        $attachments = $atts['attachments'];
        if ( is_array($attachments) && ! empty($attachments) )
        {
            // Is the $attachments array a single array of attachment data, or an array containing multiple arrays of 
            // attachment data? (note that the array may also be a one-dimensional array of file paths, as-per default usage).
            $is_multidimensional_array = count($attachments) == count($attachments, COUNT_RECURSIVE) ? false : true;
            if ( ! $is_multidimensional_array ) $attachments = [ $attachments ];
            // Work out which attachments we want to process here. If the value is an array with either 
            // a 'path' or 'path' key, then we'll process it separately and remove it from the 
            // $atts['attachments'] so that WP doesn't try to process it in wp_mail().
            foreach ( $attachments as $index => $attachment ) 
            {
                if ( is_array($attachment) && (array_key_exists('path', $attachment) || array_key_exists('string', $attachment)) ) 
                {
                    $attachment_arrays[] = $attachment;
                    if ( $is_multidimensional_array ) {
                        unset( $atts['attachments'][$index] );
                    } else {
                        $atts['attachments'] = [];
                    }
                }
            }
        }

        // Set the $wp_mail_attachments global to our attachment data.
        // We'll read this later to check if any extra attachments should
        // be added to the email. The value will be reset every time wp_mail()
        // is called.
        global $wp_mail_attachments;
        $wp_mail_attachments = $attachment_arrays;

        // We can't use the global $phpmailer to add our attachments directly in the 'wp_mail' filter callback because WP calls $phpmailer->clearAttachments() 
        // after this filter runs. Instead, we now hook into the 'phpmailer_init' action (triggered right before the email is sent), and read 
        // the $wp_mail_attachments global to check for any additional attachments to add. 
        add_action( 'phpmailer_init', function( \PHPMailer\PHPMailer\PHPMailer $phpmailer )
        {
            // Check the $wp_mail_attachments global for any attachment data, and reset it for good measure.
            $attachment_arrays = [];
            if ( array_key_exists('wp_mail_attachments', $GLOBALS) )
            {
                global $wp_mail_attachments;
                $attachment_arrays = $wp_mail_attachments;
                $wp_mail_attachments = [];
            }

            // Loop through our attachment arrays and attempt to add them using PHPMailer::addAttachment() or PHPMailer::addStringAttachment():
            foreach ( $attachment_arrays as $attachment ) 
            {
                $is_filesystem_attachment = array_key_exists( 'path', $attachment ) ? true : false;
                try 
                {
                    $encoding = $attachment['encoding'] ?? $phpmailer::ENCODING_BASE64;
                    $type = $attachment['type'] ?? '';
                    $disposition = $attachment['disposition'] ?? 'attachment';
                    if ( $is_filesystem_attachment )
                    {
                        $phpmailer->addAttachment( ($attachment['path'] ?? null), ($attachment['name'] ?? ''), $encoding, $type, $disposition );
                    }
                    else
                    {
                        $phpmailer->addStringAttachment( ($attachment['string'] ?? null), ($attachment['filename'] ?? ''), $encoding, $type, $disposition );
                    }
                } 
                catch ( \PHPMailer\PHPMailer\Exception $e ) { continue; }
            } 
            // var_dump( $phpmailer->getAttachments() ); // Debug the mail attachments, including those parsed by WP.
        });
    }
    return $atts;
});

Really nice, this should be in core. You made my day 🥇