Can't retrieve custom post type data through REST API using get_post()

Question

I'm trying to get data from a custom post type single post through REST API. With get_posts() it works fine:

function single_project($data) {
  $args = array(
    'post_type' => 'project',
    'posts_per_page'=> 1,
    'p' => $data
  );  
  return get_posts($args);
}

add_action('rest_api_init', function () {
  register_rest_route( 'project/v1', 'post/(?P<id>\d+)', array(
    'methods' => 'GET',
    'callback' => 'single_project',
    'args' => [
      'id'
    ]
  ));
});

But in my front-end I get an array and I have to get the data from the first and only item of that array, which is not nice.

get_post() sounds like the solution but for some reason it doesn't work: the ID doesn't get passed through REST API and I can't see why.

function single_project($data) {
  return get_post($data);
}

The add_action() { ... } code is identical.

Any idea why it doesn't work?

Answer 1

If you check the documentation (Adding Custom Endpoints | WordPress REST API) you'll notice that $data is actually an array and so your code fails to do what you expect it to do because you're passing an array to the get_post() function which expects either an integer (the post ID) or a WP_Post object instead.

So:

function single_project($data) {
  $post_ID = $data['id'];
  return get_post($post_ID);
}

add_action('rest_api_init', function () {
  register_rest_route( 'project/v1', 'post/(?P<id>\d+)', array(
    'methods' => 'GET',
    'callback' => 'single_project',
    'args' => [
      'id'
    ]
  ));
});