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Caching

Introduction​

Some data retrieval or processing tasks performed by your application could be CPU intensive or take several seconds to complete. When this is the case, it is common to cache the retrieved data for a time so it can be retrieved quickly on subsequent requests for the same data.

Thankfully, WPN provides an expressive, unified API for WordPress transient feature, allowing you to take advantage of their blazing fast data retrieval and speed up your web application.

Storing items in the cache​

You may use the set method on the \WPN\Cache class to store items in the cache:

use WPN\Cache;

Cache::set('key', 'value', $seconds = 10);

If the storage time is not passed to the set method, the item will be stored indefinitely:

use WPN\Cache;

Cache::set('key', 'value');

Instead of passing the number of seconds as an integer, you may also use the WPN defined constants:

use WPN\Cache;

Cache::set('key', 'value', 2 * SECONDS_IN_AN_HOUR);

Storing values from closures​

The rememberForver method may be used to store the resulting value from a Closure in the cache permanently. Since these items will not expire, they must be manually removed from the cache using the delete method:

use WPN\Cache;

Cache::rememberForever( 'key', function (): string {
    return 'Hello' . 'World';
} );

If you want the resulting value to expire, you can use the remember method and an integer for the number of seconds as the second parameter.

use WPN\Cache;

$value = Cache::remember( 'key', 2 * SECONDS_IN_AN_HOUR, function (): string {
    return 'Foo' . 'Bar';
} );
Transient Storage

Under the hood, WordPress stores transients in the options table, prefixed with _transient, resulting in a key like _transient_key. This means a database query is still required to get the value from the cache and caching is best used when multiple database queries are required. For example, an ACF repeater field.

Retrieve an item from the cache​

The Cache's get method is used to retrieve items from the cache. If the item does not exist in the cache or has expired, false will be returned.

use WPN\Cache;

Cache::get('key');

You may also use the remember function to retrieve the value from either the cache or the Closure provided.

use WPN\Cache;

$value = Cache::remember( 'key', 2 * SECONDS_IN_AN_HOUR, function (): string {
    return 'Foo' . 'Bar';
} );