Introduction to the WordPress Rest API

rest_api_create_post.php

<?php

// Set the endpoint and request method
$endpoint = '/wp/v2/posts';
$method = 'POST';

// Set the request body data
$body = array(
  'title' => 'My new post',
  'content' => 'This is the content of my new post.',
  'status' => 'publish',
);

// Make the HTTP request
$response = wp_remote_request($endpoint, array(
  'method' => $method,
  'body' => $body,
));

// Check the response and handle any errors
if (is_wp_error($response)) {
  // There was an error making the request
  echo 'Error: ' . $response->get_error_message();
} else {
  // The request was successful
  $response_body = json_decode($response['body'], true);
  echo 'Post created: ' . $response_body['title']['rendered'];
}

rest_api_custom_endpoint.php

<?php

// Create a new class that extends the WP_REST_Controller class
class Posts_By_Author_Controller extends WP_REST_Controller {
  // Register the routes and methods for the endpoint
  public function register_routes() {
    $route = '/wp/v2/posts/by_author/(?P<author_id>\d+)';
    $args = array(
      'methods' => 'GET',
      'callback' => array($this, 'get_posts_by_author'),
    );
    register_rest_route('my-plugin/v1', $route, $args);
  }

  // Define the method that handles the request and response for the endpoint
  public function get_posts_by_author($request) {
    $author_id = (int) $request['author_id'];

    // Query the database for posts by the specified author
    $posts = get_posts(array(
      'author' => $author_id,
    ));

    // Return the posts as a JSON object
    $response = new WP_REST_Response($posts);
    $response->set_status(200);
    return $response;
  }
}

// Register the custom endpoint with the WordPress API
add_action('rest_api_init', function() {
  $controller = new Posts_By_Author_Controller();
  $controller->register_routes();
});

rest_api_get_post.php

<?php

// Set the endpoint and request method
$endpoint = '/wp/v2/posts/123'; // Replace 123 with the ID of the post you want to retrieve
$method = 'GET';

// Make the HTTP request
$response = wp_remote_request($endpoint, array(
  'method' => $method,
));

// Check the response and handle any errors
if (is_wp_error($response)) {
  // There was an error making the request
  echo 'Error: ' . $response->get_error_message();
} else {
  // The request was successful
  $response_body = json_decode($response['body'], true);
  echo 'Post retrieved: ' . $response_body['title']['rendered'];
}