Wordpress REST API provides developers with a powerful tool for interacting with WordPress remotely using HTTP requests. While it inherently supports basic content types such as posts, pages, and media, there are often needs to extend the API with custom data types and endpoints to better serve the specific requirements of a project. In this article, you'll learn how to do just that.

1. Defining a Custom Data Type

The first step is to create a custom post type (CPT) if it's not already defined. This can be done using the register_post_type() function within your plugin or theme. When registering, it's crucial to set the show_in_rest argument to true to make the new data type available in the REST API.

2. Adding a Custom Endpoint

To create a new endpoint, we'll utilize the rest_api_init hook and the register_rest_route() function. This function allows you to define the method (GET, POST, etc.), the endpoint path, and the callback function to execute when the endpoint is called.

add_action('rest_api_init', function () {
    register_rest_route('myplugin/v1', '/mydata/', array(
        'methods' => 'GET',
        'callback' => 'my_processing_function',
    ));
});

3. Handling Requests

In the callback function my_processing_function, you can process the request and return the appropriate data. You can access global variables, custom database tables, or any other resources necessary for generating the response.

4. Authentication and Authorization

To secure access to custom endpoints, various authentication methods can be employed, such as Basic Auth or OAuth. To verify user permissions, you can use functions like current_user_can() within the callback function.

5. Testing and Debugging

After implementation, it's important to thoroughly test the endpoints. You can utilize tools like Postman or cURL for sending HTTP requests and verifying the proper functionality of your endpoints.

Expanding the WP REST API with custom data types and endpoints opens the door to advanced integrations and functionalities for your WordPress projects. With a bit of code, you can significantly enhance the flexibility and capabilities of your website.