Worker to Cache POST Requests Not Reflecting in Workers Analytics

Developers Workers
1

Hello Cloudflare Community,

I am experiencing an issue with caching POST requests using a worker. Below is the worker code I have in place:

export default {
  async fetch(request, env, ctx) {
    // Function to hash the request body using SHA-256
    async function sha256(message) {
      // Encode as UTF-8
      const msgBuffer = new TextEncoder().encode(message);
      // Hash the message
      const hashBuffer = await crypto.subtle.digest("SHA-256", msgBuffer);
      // Convert bytes to hex string
      return [...new Uint8Array(hashBuffer)]
        .map(b => b.toString(16).padStart(2, '0'))
        .join('');
    }

    try {
      if (request.method.toUpperCase() === "POST") {
        // Clone and read the request body
        const body = await request.clone().text();
        // Hash the request body to use it as a part of the cache key
        const hash = await sha256(body);
        const cacheUrl = new URL(request.url);
        // Store the URL in cache by appending the body's hash
        cacheUrl.pathname = "/posts" + cacheUrl.pathname + hash;
        // Convert to a GET to be able to cache
        const cacheKey = new Request(cacheUrl.toString(), {
          headers: request.headers,
          method: "GET",
        });

        const cache = caches.default;
        // Find the cache key in the cache
        let response = await cache.match(cacheKey);
        // Otherwise, fetch response to POST request from origin
        if (!response) {
          response = await fetch(request);
          // Clone the response to modify headers and store in cache
          let newResponse = new Response(response.body, response);
          
          // Ensure Cache-Control is set correctly
          newResponse.headers.set('Cache-Control', 'public, max-age=3600'); // Cache for 1 hour

          ctx.waitUntil(cache.put(cacheKey, newResponse.clone()));
          return newResponse;
        }
        // Revalidate the cache to ensure the headers are correct
        response = new Response(response.body, response);
        response.headers.set('Cache-Control', 'public, max-age=3600'); // Cache for 1 hour
        return response;
      }
      return fetch(request);
    } catch (e) {
      return new Response("Error thrown " + e.message, { status: 500 });
    }
  },
};

I have noticed in the Cache Performance section that my endpoint is being served from the cache sometimes. However, when I check the Workers Analytics dashboard, it shows that no subrequests were cached. Here are some screenshots to illustrate the issue (Cache performance at the top and worker analytics at the bottom, filtered on the specific route) :

image
image1114×1064 95.8 KB

P.S: It is my first message on the forum, apologies if the format is wrong.

Could someone please help me understand why the Workers Analytics dashboard is not showing cached subrequests despite the Cache Performance section indicating that the requests are being served from the cache?

Any assistance or pointers would be greatly appreciated!

2

I was ended up in the same situation today (using the POST example for caching, and thus cache.match), and ultimately not having the cached metrics appear under the worker cached metrics (it is still 0)

The more I read, the more I believe this is probably intended (even if we would both like to see our cache.match cache rates).
But the docs repeatedly explicitly say that the subrequest cache metrics relates to use of fetch