oliverdavies.uk/content/node.1550e619-abd2-4efe-b941-fd4e42507d51.yml

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title:
  - value: 'Caching with decorators'
created:
  - value: '2025-04-06T00:00:00+00:00'
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body:
  - value: |
      <p>As well as <a href="/daily/2025/04/05/strategies">working with different versions of an API</a>, I was able to use the same technique I wrote about yesterday to easily add a cacheable version of the API client.</p>

      <p>As they all implement the same <code>ApiClientInterface</code>, I can inject and decorate a client with another client, making one solely responsible for caching the result from the API whilst keeping the API interaction logic separate (aka <a href="/daily/2022/12/08/the-decorator-design-pattern">the Decorator design pattern</a>).</p>

      <p>Here's an example based on the code I wrote:</p>

      <pre><code class="php">final class CacheableApiClient implements ApiClientInterface {

        /**
         * The cache duration in seconds.
         */
        private const CACHE_DURATION = 3600;

        public function __construct(
          private readonly ApiClientInterface $client,
          private readonly TimeInterface $time,
          private readonly CacheBackendInterface $cache,
        ) {
        }

        public function getResults(): Collection {
          $key = $this-&gt;getCacheKey();

          $cache = $this-&gt;cache-&gt;get($key);

          if ($cache !== FALSE) {
            return $cache-&gt;data;
          }

          $result = $this-&gt;client-&gt;getResults();

          $this-&gt;cache-&gt;set(
            cid: $key,
            data: $result,
            expire: $this-&gt;time-&gt;getRequestTime() + self::CACHE_DURATION,
          );

          return $result;
        }

      }
      </code></pre>

      <p>Nothing in this instance is specific to either version of the API.</p>

      <p>This client is only concerned with retrieving and saving cache data, and delegating any other logic to the original version.</p>

      <p>With this approach, I can switch between <code>V1ApiClient</code>, <code>V2ApiClient</code> or any other version with the same methods without having to reimplement caching as that's handled within the <code>CacheableApiClient</code>.</p>

      <p>But what if I don't want to interact with the API at all?</p>

      <p>For local development, I have a <code>FakeApiClient</code> that returns a static response that I can work with.</p>

      <p>The possibilities are endless.</p>

              
    format: full_html
    processed: |
      <p>As well as <a href="/daily/2025/04/05/strategies">working with different versions of an API</a>, I was able to use the same technique I wrote about yesterday to easily add a cacheable version of the API client.</p>

      <p>As they all implement the same <code>ApiClientInterface</code>, I can inject and decorate a client with another client, making one solely responsible for caching the result from the API whilst keeping the API interaction logic separate (aka <a href="/daily/2022/12/08/the-decorator-design-pattern">the Decorator design pattern</a>).</p>

      <p>Here's an example based on the code I wrote:</p>

      <pre><code class="php">final class CacheableApiClient implements ApiClientInterface {

        /**
         * The cache duration in seconds.
         */
        private const CACHE_DURATION = 3600;

        public function __construct(
          private readonly ApiClientInterface $client,
          private readonly TimeInterface $time,
          private readonly CacheBackendInterface $cache,
        ) {
        }

        public function getResults(): Collection {
          $key = $this-&gt;getCacheKey();

          $cache = $this-&gt;cache-&gt;get($key);

          if ($cache !== FALSE) {
            return $cache-&gt;data;
          }

          $result = $this-&gt;client-&gt;getResults();

          $this-&gt;cache-&gt;set(
            cid: $key,
            data: $result,
            expire: $this-&gt;time-&gt;getRequestTime() + self::CACHE_DURATION,
          );

          return $result;
        }

      }
      </code></pre>

      <p>Nothing in this instance is specific to either version of the API.</p>

      <p>This client is only concerned with retrieving and saving cache data, and delegating any other logic to the original version.</p>

      <p>With this approach, I can switch between <code>V1ApiClient</code>, <code>V2ApiClient</code> or any other version with the same methods without having to reimplement caching as that's handled within the <code>CacheableApiClient</code>.</p>

      <p>But what if I don't want to interact with the API at all?</p>

      <p>For local development, I have a <code>FakeApiClient</code> that returns a static response that I can work with.</p>

      <p>The possibilities are endless.</p>

              
    summary: null
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