Wordpress REST response shows taxonomy categories only with ID's

Question

I'm using WP as a headless CMS with ACF en ACF-2-REST plugins. I've added categories to a post-type and when I make a GET call, it shows me all the information of a particular post including the categories, but only the ID's. If I want to match it, I have to do another call to Categories to get the information of that categories (name, parent etc).

How can I show that information instead of just the ID in a post call?

How the JSON looks now at the /activities call:

{
"id":111,
"date":"2020-01-18T15:39:27",
"date_gmt":"2020-01-18T15:39:27",
"guid":{"rendered":"https:\/\/url.be\/?post_type=activities&p=111"},
"modified":"2020-01-18T15:39:27",
"modified_gmt":"2020-01-18T15:39:27",
"slug":"walking-on-wood",
"status":"publish",
"type":"activities",
"link":"https:\/\/url.be\/activities\/walking-on-wood\/",
"title":{"rendered":"Walking on wood"},
"template":"",
"categories":[14,25,13,2,18,21,6,24],
"acf":{...}
}

What I want to show in the "categories" instead of just the numbers (from the categories call)

{
"id":3,
"count":1,
"description":"",
"link":"https:\/\/url.be\/category\/duration\/lower-than-30-min\/",
"name":"< 30 min.",
"slug":"lower-than-30-min",
"taxonomy":"category",
"parent":2,"meta":[],
"acf":[],
"_links":{"self":[{"href":"https:\/\/url.be\/wp-json\/wp\/v2\/categories\/3"}],
"collection":[{"href":"https:\/\/url.be\/wp-json\/wp\/v2\/categories"}],
"about":[{"href":"https:\/\/url.be\/wp-json\/wp\/v2\/taxonomies\/category"}],
"up":[{"embeddable":true,"href":"https:\/\/url.be\/wp-json\/wp\/v2\/categories\/2"}],
"wp:post_type":[{"href":"https:\/\/url.be\/wp-json\/wp\/v2\/posts?categories=3"},{"href":"https:\/\/url.be\/wp-json\/wp\/v2\/activities?categories=3"}],
"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}
}

Can't find any solution on the internet how I could manipulate the structure of that JSON with a custom function, would appreciate it a lot if someone point me to the right direction. Thanks!

Answer 1

As discussed in the comments section, a solution to this question is to use a custom endpoint method for the WP REST API and perform extra queries in there to get the data you need. This way, you can do all the data manipulation to get the perfect response, resulting in one REST call.

As taken from the official developer docs

Define an endpoint method and add some extra data

<?php
add_action( 'rest_api_init', function () {
  register_rest_route( 'myplugin/v1', '/author/(?P<id>\d+)', array(
    'methods' => 'GET',
    'callback' => 'my_awesome_func', //note that this is the method it will fire
    'args' => array(
      'id' => array(
        'validate_callback' => function($param, $request, $key) {
          return is_numeric( $param );
        }
      ),
    ),
  ) );


/**
 * Grab latest post by an author along with its category!
 *
 * @param array $data Options for the function.
 * @return array Post,
 */
function my_awesome_func( $data ) {

  $posts = get_posts( array(
    'author' => $data['id'],
  ) );

  if(!empty($posts)) {
    //Example of appending extra data
    foreach($posts as $post) {
       $category = wp_get_post_terms($post->ID, 'category');
       $post['category'] = $category; 
    }
    return $posts;

  } else  {
    return new WP_Error( 'no_author', 'Invalid author', array( 'status' => 404 ) );
  }

}