Migrating our Persistence to Redis

During the sprint and after talking to some mates, you realize that using a NoSQL strategy could improve the performance of your feature. Redis is one of your best friends. Go for it and show me your Listing 4:

class IdeaController extends Zend_Controller_Action
{
    public function rateAction()
    {
        $ideaId = $this->request->getParam('id');
        $rating = $this->request->getParam('rating');

        $ideaRepository = new RedisIdeaRepository();
        $idea = $ideaRepository->find($ideaId);
        if (!$idea) {
            throw new Exception('Idea does not exist');
        }

        $idea->addRating($rating);
        $ideaRepository->update($idea);

        $this->redirect('/idea/' . $ideaId);
    }
}

interface IdeaRepository
{
    // ...
}

class RedisIdeaRepository implements IdeaRepository
{
    private $client;

    public...