PHP Pseudo code showing resource handler implementation for PATCH requests.

Invitation.php

<?php

class Invitation {

  /**
   * Callback handler for HTTP Patch request.
   * @param int|null $id
   * @param Request|null $request
   */
  public function patch(int $id = NULL, Request $request = NULL) {
    // Array of actions and their corresponding action Resolvers.
    $actionResolver = [
      'accept' => 'acceptInvitation',
      'reject' => 'rejectInvitation',
      'request_change' => 'requestChangeInvitation'
    ];
    $content = $request->getContent();
    $action = $content->action ?? '' ;
    $actionArguments = $content->actionArguments ?? null;
    // Resolve and execute the relative function associated with that action.
    if (isset($actionResolver[$action])) {
      // On Success, respond with HTTP 204.
      return $actionResolver[$action]($actionArguments);
    }
    else {
      // Throw Exception HTTP 400 Bad request for invalid action name.
    }
  }
}