RTKQ selectfromresult equailty checking

[niZmosis]

I recently reworked my code so I am no longer keeping my own state in the store, trying to make it stay in sync with RTKQ. What I liked about it was being able to use useSelector which has an equaity check. I am now using selectfromresult to call the query cache. The problem is I am polling the actual query every 10 seconds (its a game) and the selectfromresult is firing everytime even though it has the same results. Is there a way i can use something like lodash isEqual with selectfromresult to prevent rerenders? Is there a different method to prevent rerenders? Thanks! Oh and RTK is awesome!

[markerikson]

Can you show what your code looks like?

selectionFromResult should be doing a shallow equality check, which means that the fields being returned need to be stable references from run to run:

https://redux.js.org/tutorials/essentials/part-8-rtk-query-advanced#selecting-values-from-results

[niZmosis]

I have noticed in other places that it does shallow checking. In this particular instance, its an array with strings. Here is the query, then the selectrfromresults.

const { data: openLubAuctions } = useGetUserLubAuctionsOpenQuery( { address: account }, { skip: !account || authLevel < 2, pollingInterval: pollingIntervalUserAuctions } )

const { previousPlacedBids } = userApi.endpoints.getUserLubAuctionsOpen.useQueryState( { address: account }, { selectFromResult: ({ data }) => ({ previousPlacedBids: data?.entities?.[auctionId]?.bidsArray?.map((bid) => fixNumberString(bid.bidNumber / 100) ) ?? [] }) } )

Im going to read over that link you sent now.

Ohh I see now. So I should create a custom memoized selector that I use with the useQueryState. I dunno how many times I've read these docs, i don't remember that one lol.

[markerikson]

Yeah, it's the .map() call that's the issue.

lastResult.previousPlacedBids !== currentResult.previousPlacedBids because they're different arrays, which is the same scenario that the link actually happens to show for why we need a memoized selector here.

[niZmosis]

Awesome, thank you.