How to Use Redis for API Caching in WooCommerce Plugin

Continuing our previous articles Caching in WordPress and Caching in WooCommerce Addons we’ll explore one more important caching i.e. Redis API Caching in WooCommerce. To implement this caching we’ll take the help of one famous PHP Library i.e. PHPfastecache.

To implement the Redis caching, please install and configure the Redis server on your system by following the official Redis installation documentation.

To verify if the Redis server is installed and running you can open the terminal and execute the command as ‘redis-cli’ If the Redis server is configured correctly, you will enter the Command Line Interface of the Redis server. Further, you hit the command `ping` you will get the response as`PONG`

You can also see all the keys stored in the Redis server cache. Use the command `KEYS *`

To make the Redis server available globally to PHP, you just need to add the redis.so shared library to the extension list of the configuration file of your PHP server. In my case, I have added the php.ini file of the Apache server. Restart of Apache server.

To verify if the Redis extension is enabled, create a PHP file in the PHP installation folder and add the content as <?php phpinfo();?> Now open this file on the browser. If the Redis server is available it will be displayed something like the below screenshot.

Now to implement Redis caching in the WordPress module (plugin or theme) we need to install PHPfastcache inside the module. For this add a composer.json file and add the below lines.

{
    "require": {
        "phpfastcache/phpfastcache": "^8.1"
    }
}

Now run the command composer install from the root folder. It will install the complete PHPfastcache library and other dependencies inside a new vendor folder.

To implement the Redis caching in the WooCommerce plugins, we have created a class `WK_Caching_PHPFastCache` and add set methods as below.

         /**
		 * Set the PHP fast cache contents by key and group.
		 *
		 * @param string $cache_key Cache key.
		 * @param mixed  $cache_value Cache value.
		 * @param string $cache_group Cache group.
		 * @param int    $expiry Default 1 hour.
		 */
		public function set( $cache_key, $cache_value, $cache_group = 'wk', $expiry = 3600 ) {
			$fast_key = '_wkwc_cache_' . $cache_group . '_' . $cache_key;

			$driver = $this->get_driver();

			if ( is_null( $this->psr_16_adapter ) ) {
				$this->psr_16_adapter = new Psr16Adapter( $driver );
			}

			$this->psr_16_adapter->set( $fast_key, $cache_value, $expiry );
		}

		/**
		 * Get the driver viz. Files, Redis, Predis, Mongodb -> https://www.phpfastcache.com/
		 *
		 * @return bool
		 */
		protected function get_driver() {
			$driver = 'Files';

			$res = exec( 'redis-cli ping' );

			if ( 'PONG' === $res ) {
				$driver = 'Redis';
			}

			return apply_filters( '_wkwc_get_fast_cache_driver', $driver );
		}

To set data in the cache we created a method `set` that accepts 4 parameters as cache key, value to cache, cache group, and the expiry time. Based on supplied cache key and cache group we created a unique cache key with some default prefix.

Next, we create an object of the Adapter class from the PHPfastcache library. This adapter requires the driver’s name. The PHPfastecache library supports multiple drivers like ‘Files’, ‘Redis’, ‘Predis’, ‘MongoDB’ etc.

In our scenario, we set up the Redis server and extension so after checking if the Redis server is running we supplied the ‘Redis’ driver otherwise ‘Files’ driver.

To get the stored data on the Redis cache server, we created a method ‘get’ as below.

       /**
		 * Get the php fast cache contents by the key & group.
		 *
		 * @param string $cache_key Cache key.
		 * @param string $cache_group Cache Group.
		 *
		 * @return bool|mixed
		 */
		public function get( $cache_key, $cache_group = 'wk' ) {
			$fast_key = '_wkwc_cache_' . $cache_group . '_' . $cache_key;

			$driver = $this->get_driver();

			if ( is_null( $this->psr_16_adapter ) ) {
				$this->psr_16_adapter = new Psr16Adapter( $driver );
			}

			WK_Caching::log( "Get PHP Fast Cache, Driver: $driver key: $fast_key, cache key: $cache_key, Cache group: $cache_group" );

			$data = $this->psr_16_adapter->get( $fast_key );

			return empty( $data ) ? false : $data;
		}

In the above code, we passed two parameters to our get method viz. ‘$cache_key’ & ‘$cache_group’ based on these params we again created the same unique key using the same prefix in the set method. And called the get method of the Adapter class.

For this article, we are concluding that Redis caching API is an efficient server caching method to provide faster results. We can implement this method for caching data to provide it on any API endpoint.

We have successfully implemented the Redis caching API for our Multi-Vendor Marketplace for WooCommerce plugin and implementing the same in our all WooCommerce extensions with their next releases.

For any technical assistance, please raise a ticket or reach us by mail at [email protected]

Also, you may Hire WooCommerce Developers for your custom project development.