v1.9 implement Concurrency to subscribe for action's result

Retrieve side effect result after dispatching an action (no more callback)

When your action trigger some side effect (like fetching API),
you can use built-in hooks dispatchResult or waitResult to dispatch and subscribe for results from action.

Use case with React:

const mapDispatchToAC = {
  fetchProfile: userId => ({ userId }),
};

const userDispatcher = createDispatcher('user', mapDispatchToAC);

// Component A
async componentDidMount() {
  const action = userDispatcher.fetchProfile(userId)
  const profile = await action.waitResult()
  // profile = { name: "Emily" }
}

In your side effect handler (example with Redux Saga):

import { take } from 'redux-saga/effects'

function* fetchProfile(action) {
  const profile = { name: "Emily" }   // call your side effect here (like API request)
  action.dispatchResult(profile)
}

function* sagaWatcher() {
  yield take(userDispatcher.fetchProfile, fetchProfile)
}

If you want to subscribe for result from other places:

// Component A calls userDispatcher.fetchProfile
// but Component B and Component C also want to subscribe for the action's result

import { waitResult } from "redux-dispatcher";

// Component B
async componentDidMount() {
  // this Promise will be resolved when dispatchResult is called.
  // if dispatchResult has already been called before, this waitResult will immediately return a cached result
  const result = await waitResult(userDispatcher.fetchProfile)
}

// Component C
componentDidMount() {
  const unsubscribe = waitResult(userDispatcher.fetchProfile, result => {
    // each time dispatchResult is called, this callback will be triggered
  })

  // to remove the callback from listening to result, simply call unsubscribe()
}

// in Component A, you can also subscribe for continuous results like in Component C
componentDidMount() {
  userDispatcher.fetchProfile(userId).waitResult(result => {
    // each time dispatchResult is called, this callback will be triggered
  })
}