Helper class for ACF and Gutenberg. Get blocks fields by passing block_id and post_id.

ACF Gutenberg get block fields

<?php
namespace JensSogaard;

class BlockHelper
{
    /**
     * Gets ACF fields for a specific block on a given post
     * @author Jens Soegaard <jens@jenssogaard.com>
     */
    public function getBlockFromPage(string $block_id, int $post_id)
    {
        $post = get_post($post_id);

        if (!$post) return false;

        $blocks = parse_blocks($post->post_content);

        foreach($blocks as $block){
            if ($block['attrs']['id'] !== $block_id) continue;

            acf_setup_postdata($block['attrs']['data'], $block['attrs']['id'], true);
            acf_reset_postdata($block['attrs']['id']);

            return get_fields();
        }

        return false;
    }

    /**
     * Return post id by checking for post instance, second POST param post_id (eg. if ACF ajax preview from Gutenberg), third GET page_id (WP preview)
     * @author Jens Soegaard <jens@jenssogaard.com>
     */
    public function getPostId()
    {
        if (get_the_ID()) return get_the_ID();
        if (isset($_POST['post_id'])) return $_POST['post_id'];
        if (isset($_GET['page_id'])) return $_GET['page_id'];

        return false;
    }
}