Using Realtime fetch

[shamxeed]

How is real-time fetching is going to affect my server performance? Is it recommended?

[TkDodo]

What is real-time fetching please?

[shamxeed]

An example here, shows that we can fetch data after every second using refetchInterval. How is that going to affect server performance and is it even recommended? Thanks!!

[TkDodo]

okay, interval fetching :)

that is up to you to decide. do you need data fetched every N seconds? N minutes? is it needed at all? depends on the use-case. I can't tell you if your server can handle it

[shamxeed]

Okay! But in the optimistic update example, the use case is for an array of strings I guess, while in my use case I'm dealing with an array of objects. If you can guide me with some workarounds I will appreciate that.

[TkDodo]

why does that matter? Optimistic updates are just:

• you do a mutation with variables of type X
• in the onMutate, you grab the current value from the cache, whatever that may be.
• you optimistically write the data in the cache. If your cache value is an array of objects, merge your variables into it at the correct place. it depends on your use-case
• return the old value from onMutate so that you can make a rollback onError
• invalidate in onSettled
• profit

[shamxeed]

Okay, thanks a lot for your time and commitment, I did it. Mind seeing how I achieve that? maybe for future references.

[TkDodo]

🥳
Sure, please share 👍

[shamxeed]

Showing just how I updated the cached query.

 queryClient.setQueryData('myInbox', old => {
      const toBeChanged = old.myInbox.find(i => i.id === inboxId)
      toBeChanged.chat = [...toBeChanged.chat, newData]
      return { ...old }
  })

BOOM!!! the cached query is been updated with the new data I passed to it. Thanks once again dude!!!!