getQueryData returns undefined even if the persisted cache is there

[frederikhors]

I'm using experimental_createPersister for IndexedDB cache.

Until a few minutes ago I was convinced that I could use method queryClient.getQueryData to get an element from the persisted cache even without the "momentary" cache being full.

I express myself with the terms "persisted" and "momentary" but I don't know if they are right.

I created a small but effective reproduction of the problem here.

Steps to reproduce:

1. Open the first page of the app:

   

2. Click on "John" and on "Bob" links

3. The "persisted" cache and the "momentary" cache are filled now

4. Go to the Home page again

5. RELOAD THE PAGE

6. Click on the button "Try to get Player 2 from the cache"

7. See the message in console: undefined, DAMN!

Why?

If you open the browser Dev Tools you can see in the IndexedDB the cache is there, filled up!

Why is Bob undefined?

Is getQueryData getting only from the "momentary" cache?

[TkDodo]

Is getQueryData getting only from the "momentary" cache?

essentially, yes. getQueryData and setQueryData are synchronous functions that read from the in-memory cache. Thus, they cannot read from a persistent cache, because that would per definition be asynchronous.

This is essentially the same reason why setQueryData doesn't persist data, so it's related to:

• setQueryData() should be persisted too, right? #6310

If you want immediate cache restoration, please use the PersistQueryClientProvider. the createPersister api is meant for lazily filling the queryCache at the first time when the queryFn runs. You can run it with queryClient.ensureQueryData(). This will read from the in-memory cache, and run the queryFn (thus reading from the persistent cache) if there is no data loaded yet.

You can't have the cake and eat it, too :)

[frederikhors]

If you want immediate cache restoration, please use the PersistQueryClientProvider.

Can I use it with Svelte too?