Laravel Redis Sorted Set Paginator

Ever wanted to display paginated sorted sets at scale? A great example of this would be a leaderboard for a game, or for a website with a large userbase. This package will create a Laravel LengthAwarePaginator from a Redis sorted set. As a sorted set, by definition, is always sorted, it allows a large number of records to be paginated, with very little overhead.

Installation

You can install the package via composer:

composer require ge-tracker/laravel-redis-paginator

Usage

Initialise the paginator by using dependency injection or the provided RedisPaginator facade. The example below will interact with the leaderboard sorted set. We leverage Laravel's Redis interface, which will honour any prefixing and clustering options that you have configured on your application.

Here is an example of a paginated sorted set in action:

public function index(LaravelRedisPaginator $redisPaginator)
{
    $users = $redisPaginator->perPage(25)->paginate('leaderboard');

    return view('leaderboard', compact('users'));
}

Sorting

The sortAsc and sortDesc methods allow you to choose the order of the returned results. The default sorting is in ascending order.

$usersAsc = $redisPaginator->sortAsc()->paginate('leaderboard');

$usersDesc = $redisPaginator->sortDesc()->paginate('leaderboard');

Get the rank and page for a user

You may want to display the user's rank in the sorted set, as well as a link to jump to the page that contains their name. This can be achieved by using the rank() method. A MemberRank object will be returned which contains the score, rank, and page properties:

public function show(User $user, LaravelRedisPaginator $redisPaginator)
{
    $memberRank = $redisPaginator->rank('user:' . $user->id, 'leaderboard');

    dump($memberRank->score, $memberRank->rank, $memberRank->page);
}

Using the facade

For those of you who prefer facades over dependency injection, that option is also available:

public function index()
{
    $users = RedisPaginator::perPage(25)->paginate('leaderboard');

    return view('leaderboard', compact('users'));
}

Selecting a page to view

The current page can be set by using the page() method, or by using the method parameters. Under the hood, the package uses Laravel's default Paginator's page resolution, which means that the page can also be specified via the query string.

// Using the fluent interface
$users = $redisPaginator->page(5)->paginate('leaderboard');

// Using method parameters
$users = $redisPaginator->paginate('leaderboard', 'page', 5);

// https://www.example.com/leaderboard?page=5
$users = $redisPaginator->paginate('leaderboard');

Resolving Eloquent models

Given that Redis an in-memory data structure store, and not a relational database, it is very likely that the real data relating to your paginated data (leaderboard?) is not wholly stored in Redis. This data will need to be loaded once you have fetched your paginated results, and this package will handle that for you.

In this example, we assume that you have stored your data in the following format:

member	score	Eloquent ID
user:1	100	1
user:2	200	2
user:3	300	3

First, create a Redis resolver. This can be placed anywhere your application, such as app/RedisResolvers/UserResolver.php.

The $modelKey property should correspond to the key that you are using to generate your Redis members. This will generally be id or uuid. The $scoreField property defines the field that will be mapped onto your Eloquent model, or merged into your results array.

<?php

namespace App\RedisResolvers;

use App\User;
use GeTracker\LaravelRedisPaginator\Resolvers\AbstractResolver;

class UserResolver extends AbstractResolver
{
    // Defaults shown below, can be omitted
    protected $modelKey = 'id';
    protected $scoreField = 'score';

    /**
     * Load Eloquent models
     */
    protected function resolveModels(array $keys)
    {
        return User::whereIn('id', $keys)->get();
    }

    /**
     * Resolve a key from Redis to an Eloquent incrementing ID or UUID
     */
    protected function resolveKey($key)
    {
        return (int)str_replace('user:', '', $key);
    }
}

The resolveKey() method will take a single key (Redis member), and allow you to transform it. In the example above, we are stripping user: from the string, before casting it to an integer.

You can then define resolveModels() that accepts an array of resolved keys to be queried.

Finally, we must set our model resolver before running the query:

$users = $this->paginator
    ->setModelResolver(new \App\RedisResolvers\UserResolver())
    ->paginate('leaderboard');

We can now access our full User model, as well as the score that has been loaded from Redis:

echo $users[0]->name . ' -> ' . $users[0]->score;

Testing

composer test

Changelog

Please see CHANGELOG for more information on what has changed recently.

Contributing

Please see CONTRIBUTING for details.

Security

If you discover any security related issues, please email james@ge-tracker.com instead of using the issue tracker.

Credits

• James Austen
• All Contributors

License

The MIT License (MIT). Please see License File for more information.