Creating a WordPress REST API with PHP code

What is WordPress REST API?

Before moving on to “Creating a WordPress REST API with PHP code“, let’s talk about what a REST API is. WordPress REST API is a structure that allows you to programmatically access data in the WordPress database. The REST API allows you to access WordPress items (such as posts, pages, and comments) by sending HTTP requests and allows you to make changes to these items. This allows you to interact with your WordPress content with third-party applications and create custom applications using the data in the WordPress database.

The WordPress REST API includes “endpoints” that return lists of WordPress items and allow you to filter those items. For example, the /wp-json/wp/v2/posts endpoint returns a list of all posts and using a query like /wp-json/wp/v2/posts?author=123 allows you to display only the posts by a specific author.

The WordPress REST API also allows you to make changes to items. For example, you can send a POST, PUT, or PATCH HTTP request to change the title of a post.

Creating a WordPress REST API with PHP code?

Here is an example of how to create a REST API endpoint in WordPress using code:

1. First, install and activate the “REST API” plugin in WordPress. This plugin enables and adds REST API functionality to WordPress.
2. Next, create a plugin or add a “functions.php” file to your current theme to create your own custom REST API functions.
3. Add the following code to your functions.php file to create a REST API endpoint:

function custom_rest_endpoint() {
  register_rest_route( 'custom/v1', '/endpoint', array(
    'methods' => 'GET',
    'callback' => 'custom_endpoint_callback'
  ) );
}
add_action( 'rest_api_init', 'custom_rest_endpoint' );

4. Define a “callback” function for the endpoint. This function determines the data that will be returned when the user calls the endpoint:

function custom_endpoint_callback() {
  return 'Hello World!';
}

After completing these steps, your custom REST API endpoint will be ready to use. For example, you can go to the address http://yoursite.com/wp-json/custom/v1/endpoint to view the message “Hello World!”

For more information and example code, you can check out the official WordPress documentation:

• https://developer.wordpress.org/rest-api/
• https://developer.wordpress.org/rest-api/extending-the-rest-api/

BONUS: How to create Meta Boxes in WordPress? With PHP code.