WordPress REST API: routes, endpoints, and request parameters

The WordPress REST API is a strong replacement for the admin-ajax API in core. It lets you structure the way data goes into and out of WordPress instead of routing everything through a single action parameter, which usually means less plumbing code and cleaner AJAX calls.

Routes and endpoints

A route is the URI that can be matched to different HTTP methods (GET, POST, DELETE and so on).

The mapping of an individual HTTP method to a route is known as an endpoint. In other words, “route” refers to the URL, whereas “endpoint” refers to the function behind it that corresponds to a particular method on that URL.

To see all registered routes and endpoints of a site:

// With pretty permalinks:
http://oursite.com/wp-json/

// Otherwise:
http://oursite.com/?rest_route=/

Registering a route

Routes are registered on the rest_api_init hook:

add_action( 'rest_api_init', function () {
    register_rest_route( 'shops-script/v1', '/update', [
        'methods'  => 'POST',
        'callback' => 'my_function',
    ] );
} );

The first argument is the namespace — always prefix it with your plugin or project name to avoid collisions with other extensions.

Reading parameters

The callback receives a WP_REST_Request object:

function my_awesome_func( WP_REST_Request $request ) {

    // Parameters are accessible via direct array access on the object:
    $param = $request['some_param'];

    // Or via the helper method:
    $param = $request->get_param( 'some_param' );

    // The combined, merged set of parameters:
    $parameters = $request->get_params();

    // The individual sets of parameters are also available, if needed:
    $parameters = $request->get_url_params();
    $parameters = $request->get_query_params();
    $parameters = $request->get_body_params();
    $parameters = $request->get_json_params();
    $parameters = $request->get_default_params();

    // Uploads aren't merged in, but can be accessed separately:
    $parameters = $request->get_file_params();
}

If the request has the Content-Type: application/json header set and a valid JSON body, get_json_params() returns the parsed body as an associative array.

Docs

• open_in_new REST API Handbook .