Dispatch before transforming

[ta-le]

I have a query where the fetch response is transformed using transformResponse.
I also want to search the original (not the transformed) response for some data to add to another Redux slice (meaning I need the dispatch API).

Since dispatch is not available from transformResponse, is there another place where I have access to the original response + dispatch?

Thanks in advance!

[EskiMojo14]

in your other slice, you can respond to the original endpoint fulfilled action, which will have the response instance attached.

const slice = createSlice({
  ...config,
  extraReducers(builder) {
    builder.addMatcher(api.endpoints.getPost.matchFulfilled, (state, action) => {
      const { response } = action.meta.baseQueryMeta
      try {
        const json = response.json();
      } catch {}
    })
  }
})

alternatively if you wanted to do this in a place where you have access to dispatch, you could use a listener.

[ta-le]

Thanks, that's exactly what I was looking for!

However, I'm now running into the problem that json() actually needs to be awaited for. From my understanding, it's not allowed to run async code in here, is it?

[EskiMojo14]

hmm, you're right.

honestly i'd probably do something like

transformResponse: (response) => ({ original: response, transformed: transform(response) })

const slice = createSlice({
  ...config,
  extraReducers(builder) {
    builder.addMatcher(api.endpoints.getPost.matchFulfilled, (state, action) => {
      const { original } = action.payload
    })
  }
})

it does mean that you'd have to deal with selecting out transformed when you call the hook, but I think this is still the simplest way.

[ta-le]

Yes that's always a solid plan B!

With the solution above, running reponse.json() also runs into TypeError: Already read error, the body is already used by RTK Query.
However, in the action.meta.baseQueryMeta.response data there are _bodyInit and _bodyText. They contain what you would expect when doing response.text() as a string (the unparsed JSON data).

Is it wise to use those?

[phryneas]

I fear not - those are probably implementation details of your runtime or a polyfill you are using.