The Redis is an in-memory key value that can be used as a cache or store.

Depending on the circumstances, we could consider using Redis as a store for our Aggregates.

To get started, make sure you have a PHP client to connect to Redis. A good one that we recommend is Predis:

composer require predis/predis:~1.0
namespace InfrastructurePersistenceRedis;

use DomainModelPost;
use DomainModelPostId;
use DomainModelPostRepository;
use PredisClient;

class RedisPostRepository implements PostRepository
{
    private $client;

    public function __construct(Client $client)
    {
        $this->client = $client;
    }

    public function save(Post $aPost)
    {
        $this->client->hset(
            'posts',
            (string) $aPost->id(), serialize($aPost)
        );
    }

    public function remove(Post $aPost)
    {
        $this->client->hdel('posts', (string) $aPost->id());
    }

    public function postOfId(PostId $anId)
    {
       if($data = $this->client->hget('posts', (string) $anId)) {
          return unserialize($data);
       }

       return null;
    }

    public function latestPosts(DateTimeImmutable $sinceADate)
    {
        $latest = $this->filterPosts(
            function(Post $post) use ($sinceADate) {
                return $post->createdAt() > $sinceADate;
            }
        );

        $this->sortByCreatedAt($latest);

        return array_values($latest);
    }

    private function filterPosts(callable $fn)
    {
        return array_filter(array_map(function ($data) {
            return unserialize($data);
        },

        $this->client->hgetall('posts')), $fn);
    }

    private function sortByCreatedAt(&$posts)
    {
        usort($posts, function (Post $a, Post $b) {
            if ($a->createdAt() == $b->createdAt()) {
                return 0;
            }
            return ($a->createdAt() < $b->createdAt()) ? -1 : 1;
        });
    }

    public function nextIdentity()
    {
        return new PostId();
    }
 }