Updating state managed by another reducer

Question

In my React app, my appReducer manages global stuff such as notifications, user info, etc.

One of the modules in the app is the inventory module which has its own reduce

Answer 1

In Redux official document there's a chapter called 'Beyond combineReducers'. It mentioned about Sharing data between slice reducers.

https://redux.js.org/recipes/structuring-reducers/beyond-combinereducers#sharing-data-between-slice-reducers

I personally prefer the third solution mentioned in the link, which is adding a third customized reducer to handle the "special" cases where data needs to be shared across slices, then use reduce-reducers to combine the new customized reducer and the original combined reducer (i.e. appReducer + inventoryReducer).

const crossSliceReducer = (state, action) => {
  if (action.type === 'CROSS_SLICE_ACTION') {
    // You can access both app and inventory states here
  }
  return state;
}
// Combine the reducers like you did before
const combinedReducer({app: appReducer, inventory: inventoryReducer});

// Add the cross-slice reducer to the root reducer
const rootReducer = reduceReducers(combinedReducer, crossSliceReducer)