How transform data from two endpoints?

[acanimal]

Hi, I'm using RTKQuery and need a bit of help.
Right know I my createApi has two query endpoints, one to query data to firebase and one to query data on my backend API. The two sets of data are "related" and I would like to have it "merged" in the same state filed.
I know I have the transformResponse but it is only usefull to transform the response of an API before store in the state, what I need is a bit more complicated.
Can someone give some ideas on how to handle this?
Thanks!

[markerikson]

Can you give an example of the data and what you mean by "merged" in this case?

[acanimal]

Yes, sorry I'll try to clarify a bit more our scennario.

Our app uses two backends:

• our own REST-API to store info about users, relationship, etc and
• firebase to store chats among users (using firebase real-time-database).

The thing is in the app we have created two RTKQuery endpoints: one to get the conversations of a user from firebase and one to get the users info from our REST API.

Our idea is to "merge" both data when the REST API call is completed and transform the users info "adding" some info that we obtain from firebase.
Is that possible? Is that a "correct" strategy?

[rrajaste]

I've solved a similar problem before by creating an endpoint that does both queries with queryFn and returns the transformed data. You can make multiple API calls inside one queryFn and parse the data how you like. You don't need to use transformResponse at all if you do this.

You can also update one endpoint's cache from another endpoint with api.util.updateQueryData.

[markerikson]

The other option is to have the two separate cache entries in RTKQ, and combine them using selectors. But yeah, making two requests in a queryFn is an option too. You could even do that by defining the two initial endpoints in RTKQ, and then dispatching the api.endpoints.someEndpoint.initiate() thunks to do the fetching inside of queryFn so you don't have to write that fetching logic entirely yourself.