createSlice reducer types

Hi,

I’ve been using a utility type like this for a while:

import { CaseReducer, PayloadAction } from '@reduxjs/toolkit'

export type MapReducerPayloads<State, ReducerPayloadMap> = {
  [K in keyof ReducerPayloadMap]: CaseReducer<State, PayloadAction<ReducerPayloadMap[K]>>
}

Which allows you to succinctly create a CaseReducers type like so:

interface RoomState {
  id: string | null;
  peer?: Peer;
  owner?: boolean;
  connections: string[];
}

type Reducers = MapReducerPayloads<RoomState, {
  createRoom: void;
  joinRoom: {
    roomId: string;
    owner: boolean;
  };
}>

const initialState: RoomState = {
  id: null,
  connections: []
}

export const roomSlice = createSlice<RoomState, Reducers>({
  name: 'room',
  initialState,
  reducers: {
    createRoom: (state) => {},
    joinRoom: (state, { payload: { roomId, owner } }) => {
      state.id = roomId
      state.peer = new Peer(roomId)
      state.owner = owner
    }
  }
})

I really like this approach as you get the types flowing through into your payload objects inside your reducers functions.

Just wanted to ask:

A) Is there a similar, built-in way of accomplishing the same? (without defining the reducers outside of the createSlice fn and letting the types get inferred - I find this less readable too)

B) Is this a pattern the maintainers would be interested in incorporating into the lib? Or is it too subjective/niche/complex etc?

Cheers

[ceuk]

Ah, I probably should have checked that first, I humbly withdraw my suggestion 😄

[phryneas]

Well, to be fair we do say so in the docs 😉

Here for example: https://redux-toolkit.js.org/usage/usage-with-typescript#defining-the-initial-state-type