Help! Cannot figure this out.

I have built a plugin based on this tutorial that gives a user the ability to export a post from a custom post type into a formatted PDF using FPDF.

As it stands, the PDF export works, but the current post is not being passed to the plugin function. A button is added to the post via a custom shortcode. When clicking the button, it is supposed to automatically take the currently viewed post and produce a PDF of the content. I can input a specific post ID into the function and it exports that specific post as intended. If I just use get_post with no argument, it exports a PDF of post with ID=1 that has already been trashed, regardless of which post the shortcode button is in.

As an FYI, the posts are loaded via AJAX, so could the problem have something to do with that?

What am I doing wrong?! Is there a better way to do this? I appreciate your help!


* Plugin Name: [redacted]
* Description: A plugin created to apply PDF export functionality to documents.
* Version: 1.0
* Author: [redacted]

if ( ! defined( 'ABSPATH' ) ) {

include( 'lsmg-pdf-helper-functions.php');

$pdf = new PDF_HTML();

if( isset($_POST['generate_posts_pdf'])){

function output_pdf() {

$post = get_post();

    global $pdf;
    $title_line_height = 10;
    $content_line_height = 8;

        $pdf->AddFont( 'Lato', '', 'Lato-Regular.php' );
        $pdf->AddFont( 'Lato', 'B', 'Lato-Bold.php' );
        $pdf->AddFont( 'Lato', 'I', 'Lato-Italic.php' );
        $pdf->SetMargins(12.7, 12.7);

        $pdf->SetFont( 'Lato', 'B', 24 );
        $pdf->Write($title_line_height, $post->post_title);

        $pdf->Line(14, 27, 40, 27);

        // Add a line break

        // Image
        $page_width = $pdf->GetPageWidth() - 20;
        $max_image_width = $page_width;

        $image = get_the_post_thumbnail_url( $post->ID );
        if( ! empty( $image ) ) {
            $pdf->Image( $image, null, null, 100 );
        // Post Content
        $pdf->SetFont( 'Lato', '', 10 );


function lsmg_pdf() {
<div class="wrap">
<form method="post" id="as-fdpf-form">
    <button class="custom-botton" type="submit" name="generate_posts_pdf" value="generate">Download PDF</button>

function register_shortcodes(){
add_shortcode('fpdf-doc', 'lsmg_pdf');

add_action( 'init', 'register_shortcodes');

1.) First, when creating a shortcode, you must return data, not print.

2.) Yes, you must explicitly specify the post id, print the id in the button or form of your shortcode, you can also use the shortcode attributes to generate a button for a specific post (See example)

Your shortcode code should be like this:

function lsmg_pdf($args) {
    global $post;
    $attrs = shortcode_atts([
        'pid' => $post -> ID
    ], $args);

    return "<div class='wrap'>
        <form method='post' data-pid='".$attrs['pid']."' id='as-fdpf-form'>
            <button class='custom-botton' type='submit' name='generate_posts_pdf' value='generate'>Download PDF</button>

Global use: (Current post)


With a specific post:

[fpdf-doc pid=1]

Also you need to change your ajax function and send a post id from data-pid tag to the server each time after pressing the button

$('.custom-botton').on('click', function(e) {
    let POST_ID = $(this).parents('[data-pid]').data('pid');

    $.post(ajax_url, {
        action: 'generate_posts_pdf',
        pid: POST_ID

And use it in get_post function on the server

add_action('wp_ajax_generate_posts_pdf', 'output_pdf');

function output_pdf() {
   $post = get_post($_POST['pid']);
| improve this answer | |
  • First and foremost, I really appreciate you offering your insight. @unbywyd Unfortunately I seem to still have an issue. I applied the suggestions you made and I receive an error of 'Too few arguments" on the output_pdf function. I'm at a dead-end here. – PepeLePew Aug 26 at 19:43
  • What I suggested is the only working option, but the fact that I did not write all the code for you, yes, it is true – Unbywyd Aug 26 at 20:02
  • Ok, thanks for your help. – PepeLePew Aug 26 at 20:06
  • See at the end of my answer, perhaps understanding will come – Unbywyd Aug 26 at 20:07
  • You are right, I confused with rest_api you need $_POST – Unbywyd Aug 26 at 20:16

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