Customizing fetchCacheKey using CacheHandler option

[dongwonnn]

Goals

1. When using an external cache store (e.g., Redis), I want to directly access the store to purge the cache key instead of revalidating.
2. In this case, I want to customize the cache key encoding algorithm so that developers can manage the key themselves (because there is a possibility that the existing cache key encoding algorithm might change).

Non-Goals

None

Background

Please consider the following two situations.

1. Using the CacheHandler option to utilize Redis as a cache store.
2. In a CMS, the router handler is used to undergo a revalidate process.

When updating data in the CMS, a revalidate process is initiated using the router handler. In this case, a user can forcibly access the router handler to revalidate, and I want to prevent this.

However, if Redis is used, this process could be omitted. After updating data in the CMS, accessing Redis to delete the specific cache key would suffice. Currently, the same key can be obtained using the implemented fetchCacheKey method, but it would be inconvenient to continuously track this method if the encoding algorithm changes.

Therefore, I'm considering allowing developers to customize the algorithm inside fetchCacheKey. I want to manage the cache key using the same encoding algorithm in both the Next.js project and the CMS.

Is it a feasible method?

Proposal

1. If fetchCacheKey is not customized, the existing fetchCacheKey should be used.
2. If fetchCacheKey is customized, it would be beneficial to allow the fetchCacheKey logic within Next.js to utilize the customized fetchCacheKey.

ref) https://nextjs.org/docs/app/building-your-application/deploying#configuring-caching

    // cache-handler.js
    module.exports = class CacheHandler {
      .... // constructor, get, set, revalidateTag 
    
      async fetchCacheKey(url, init) { 
        const customCacheKey = setCustomCacheKey();
        return customCacheKey
    }