How to manipulate the data returned via PUT in a db-connected REST service created via Apigility.

Module.php

<?php
// Assume the controller service name is Api\V1\Rest\Foo\Controller.
// Do this in your Api\Module class:

public function onBootstrap($e)
{
    $app = $e->getApplication();
    $events = $app->getEventManager();
    $sharedEvents = $events->getSharedManager();

    $sharedEvents->attach('Api\V1\Rest\Foo\Controller', 'update.post', array($this, 'onUpdatePost'));
}

/**
 * @param \ZF\Rest\ResourceEvent $e
 */
public function onUpdatePost($e)
{
    $halResource = $e->getParam('resource');
    $entity =& $halResource->resource;

    // manipulate $entity at this point to the structure you want
}