Ajax best approach

Hi folks,

I need some advice on using Ajax with WordPress as I’ve read, watched and experimented with different techniques and I’m not clear on the best approach.

I am new to WordPress development and web development in general, so I don’t want to fall into any pits later on, so any guidance would be appreciated.

After watching a YouTube video https://www.youtube.com/watch?v=OwBBxwmG49w, it seems that the best appoach is to use the Rewrite API.

So, I wrote code to create the necessary endpoints etc for the required small API, all GET requests.

  add_action('init', function () {
    add_rewrite_tag('%cpt_id%', '([0-9]+)');
    add_rewrite_tag('%cpt%', '([a-z]+)');

    add_rewrite_rule(self::API_BASE_URL . '([a-z]+)/([0-9]+)/?', 'index.php?cpt=$matches[1]&cpt_id=$matches[2]', 'top');
    add_rewrite_rule(self::API_BASE_URL . '([a-z]+)/?$', 'index.php?cpt=$matches[1]', 'top');
  });

  add_filter( 'query_vars', function ($vars) {
    array_push($vars, 'make', 'plug_type');
    return $vars;
  });

This seems to work so far with the limited testing, allowing me to route depending on the custom post type but I do feel that I’m implementing a REST API that’s already available albeit that supplies much more data than necessary. Although you can use the query variable _fields to limit data. But then to get the featured image would be another call as far as I can tell.

Someone said to use WP_Query object too but I’m far more comfortable using SQL directly on $wpdb, which is easy enough to do for the above:

$results = $wpdb->get_results("SELECT posts.post_title, posts.ID, meta.meta_value AS img_src FROM $wpdb->posts AS posts LEFT JOIN $wpdb->postmeta ON post_id = posts.ID AND meta_key = '_thumbnail_id' LEFT JOIN $wpdb->posts AS attachment ON attachment.ID = meta_value LEFT JOIN $wpdb->postmeta as meta ON meta.post_id = attachment.ID AND meta.meta_key = '_wp_attached_file' WHERE posts.post_type = 'makes';", OBJECT_K);

Probably should have done a subquery but the above works.

So, my question is do I use:

1) The WP REST API.

2) The Rewrite API and $wpdb, which I have sort of working now.

3) A PHP file using require_once(“wp-load.php”); and $wpdb called directly. This seems to work but I’m unsure about security.

<?php
  require_once("wp-load.php");

  global $wpdb;

  $results = $wpdb->get_results("SELECT posts.post_title, posts.ID, meta.meta_value AS img_src FROM $wpdb->posts AS posts LEFT JOIN $wpdb->postmeta ON post_id = posts.ID AND meta_key = '_thumbnail_id' LEFT JOIN $wpdb->posts AS attachment ON attachment.ID = meta_value LEFT JOIN $wpdb->postmeta as meta ON meta.post_id = attachment.ID AND meta.meta_key = '_wp_attached_file' WHERE posts.post_type = 'makes';", OBJECT_K);

  $message = json_encode($results);

  wp_send_json_success([
    'message' => $message
  ]);
?>

I haven’t even attempted to try the admin-ajax.php option due to the YouTube video showing how slow it is compared to the other options and from what I’ve “skim” read seems complex anyway.

I appreciate anyone spending their time to advise me on this.