Verifying that the Cache Handler works

You can verify if the cache handler is active by using either of the following methods:

Method 1: Console Logging

Add console.log statements to your cache handler:

/* ... */
const handler = {
  name: 'my-cache-handler',
  async get(key) {
    console.log('handler.get', key);
    return cacheStore.get(key);
  },
  async set(key, value) {
    console.log('handler.set', key, value);
    cacheStore.set(key, value);
  },
};
/* ... */

Execute your application as usual:

npm run build
npm run start

The console should display the output the application starts and any page is opened in your browser:

handler.get ...
handler.set ...

Method 2: Debug Mode

Activate debug mode by setting the NEXT_PRIVATE_DEBUG_CACHE environment variable:

Locate or create a .env.local file in your project's root directory and add the following:

NEXT_PRIVATE_DEBUG_CACHE=1

Build and execute your application:

npm run build
npm run start

A verbose output should appear in your server console when the application starts and any page is opened in your browser:

using custom cache handler @neshca/cache-handler is not configured yet
[CacheHandler] Instance created with provided context.
[CacheHandler] Creating new CacheHandler configuration.
Connecting Redis client...
[CacheHandler] Cache configuration retrieved from onCreation hook.
Redis client connected.
[CacheHandler] [handlers: [redis-stack]] Successfully created CacheHandler configuration.
[CacheHandler] [method: get] [key: /app/with-params/dynamic-true/200] Started retrieving value in order.
[CacheHandler] [handler: redis-stack] [method: get] [key: /app/with-params/dynamic-true/200] Started retrieving value.

Note: During the build stage, it's normal to see @neshca/cache-handler is not configured yet several times.

Troubleshooting

If the cache handler is not active:

1. Verify that the cache handler has been correctly installed, imported, and configured. Refer to the Installation and the First Steps section for guidance.

2. Ensure that the NEXT_PRIVATE_DEBUG_CACHE environment variable is set. To verify, add the following to your next.config.js file:

   next.config.js

   console.log('NEXT_PRIVATE_DEBUG_CACHE', process.env.NEXT_PRIVATE_DEBUG_CACHE);

   When you build or run your application, NEXT_PRIVATE_DEBUG_CACHE 1 should appear in your console.

3. If you're using a third-party library to retrieve data or database records (e.g., axios, node-fetch, pg) within the App directory, ensure you're using the unstable_cache ↗ (opens in a new tab). By default, Next.js will cache only native fetch calls.