How to use Spatie's response cache with Statamic

I think Spatie's response cache package should be used on more pages. The speed improvement is impressive, and even on highly dynamic pages, data is read more often than it is written or changed - a lot of room for improvement.

On static pages, the package should be a real no-brainer. When using it with dynamic content, like with my favorite CMS Statamic (❤️), there is this dreaded, scary thing called cache invalidation. When and how should we clear the cache when content changes? The saying goes:

Only 2 things in development are hard:
Naming things, cache invalidation and off-by-one errors

Luckily I found a really simple way of integrating it!

¶Enough Talk

To keep this post short for change, let me get right to it:

Of course, you need to have a working version of Statamic installed. In your project, also install the response cache package by running

composer require spatie/laravel-responsecache

After that, you need to add the middleware to your web group to apply the cache to all your (GET) routes. See the docs for more information and options.

// app/Http/Kernel.php

...

protected $middlewareGroups = [
   'web' => [
       ...
       \Spatie\ResponseCache\Middlewares\CacheResponse::class,
   ],

Now here is the kicker: To clear the cache everytime something is updated in the Statamic backend, you need to create a new Event Subscriber that clears the cache after a "something happened in Statamic" event. Create and place the following file wherever you want:

// app/Subscribers/ResponseCacheStatamicSubscriber

<?php

namespace App\Subscribers;

use Spatie\ResponseCache\Facades\ResponseCache;
use Statamic\Events\Concerns\ListensForContentEvents;

class ResponseCacheStatamicSubscriber
{
    use ListensForContentEvents;

    /**
     * Register the listeners for the subscriber.
     *
     * @param \Illuminate\Events\Dispatcher $events
     */
    public function subscribe($events)
    {
        foreach ($this->events as $event) {
            $events->listen($event, self::class.'@clear');
        }
    }

    /**
     * Commit changes.
     *
     * @param mixed $event
     */
    public function clear()
    {
        if (config('responsecache.enabled')) {
            ResponseCache::clear();
        }
    }

}

The whole magic here is happening in the trait Statamic\Events\Concerns\ListensForContentEvents where the Statamic team keeps all the Events neat and tidy for you need to listen for.

Then simply add this subscriber to the EventServiceProvider and you are already done! Your cache is cleared and rebuild on every update, but most users will get a lightning fast response 👍

//App\Providers\AppServiceProvider


use App\Subscribers\ResponseCacheBuster;
use Illuminate\Foundation\Support\Providers\EventServiceProvider as ServiceProvider;
use Statamic\Git\Subscriber;

class EventServiceProvider extends ServiceProvider
{
    // ...

    protected $subscribe = [
        ResponseCacheStatamicSubscriber::class
    ];

    // ...
}

¶During Development

Just a quick note because I tend to forget this way to often: Remember to add a line to your local .env file that you do not want to use the response cache there.

# .env
...
RESPONSE_CACHE_ENABLED=false
...

¶Why though?

You may ask "why the hassle, Statamic already comes with a pretty good cache". You are right, and in essence this approach should yield quite similar results like the Application Driver approach of the build in Statamic cache.

I found a little speed improvement using Spatie's library though, but this could be because I mostly create Statamic sites with Blade instead of using Antlers, the Statamic templating engine.

If you use this or not, I just wanted to share what I learned 🎉

Best! Simon