`onCacheHit` callback when query result is found in Apollo cache

[alessio-mms]

The Problem

When using cache-first fetch policy I often require side-effects as result of querying data. The onCompleted callback generally addresses this problem, but only triggers when data is fetched from the server and not from cache. Currently, to address this problem, I need to implement a custom solution or change the fetch policy to cache-and-network, which obviously means we no longer gain the benefit from caching the data.

The Solution

Introduce an additional callback onCacheHit (Or something similar) that allows side-effects as a result of a query returning a result from cache.

Why is it better?

No custom solutions required for detecting Apollo client cache hits. This really would fix the headaches I get working with apollo client.

[dbehmoaras]

Any update on this? We are running into the same problem where we need to rely on the onCompleted callback which, as mentioned above, does not run when retrieving data from the cache. In our use case, we do not care about whether the result was retrieved from the cache or through a network call. We need to run the onCompleted callback in all cases or, as suggested here, provide an onCacheHit callback.

Frankly I'm a bit dismayed that Apollo decided that this should be the default behavior without exposing any kind of override.

[dbehmoaras]

Following up to share that it appears that Apollo has pretty much flat out ignored this request since it has been an outstanding bug for YEARS. They just close the issue and do nothing. See below for just two of several examples: https://github.com/apollographql/react-apollo/issues/2177 https://github.com/apollographql/react-apollo/issues/3488

[cfator]

Also here scratching my head as to how something so fundamental has been purposely overlooked.