RTK Query Streaming updates: Waiting for the initial call and subscription to websocket stream race

[mdeperas]

Hi, thank you for your hard work with this fantastic library.

I have a question about streaming updates and how they work. My understanding from the docs is that:

• associated query will be fired off based on the query property to fetch the initial data for the cache,
• meanwhile, the asynchronous onCacheEntryAdded callback will begin, and create a new WebSocket connection.

So we want to fill in the cache data, then we are listening to the websocket events.

1) Is it possible that between the moment that initial call returns the data and the moment when we start to listen to websocket events, some data will be sent through websocket channel and it will be lost?

2) Is it possible to change the order of actions and first subscribe to websocket channel and then fire the query to API? Does it makes any sense to do that in case of the problem described in the point 1?

Thanks for any help.

[markerikson]

Yeah, we've got this described in https://redux-toolkit.js.org/rtk-query/usage/streaming-updates#using-the-oncacheentryadded-lifecycle :

Typically, you will await cacheDataLoaded to determine when the first data has been fetched, then use the updateCacheData utility to apply streaming updates as messages are received.

[mdeperas]

Thanks for the answer. I've read the docs and I understand the typical scenario.

My concern is that I may loose some data that would be sent between the moment the initial call will feed the cache and I will start listening to the websocket events. Is it even worth to consider such scenario or it is not likely to happen?

[mdeperas]

Is it possible to apply opposite scenario? First listen to streaming updates and then ask for the cache data to load?

[mdeperas]

Thanks @markerikson