Is there a way to wait for an action in redux-sagas?

Question

I have a saga (A) which fetches the API. This is tied with action (a). I want to trigger an action (b) which internally calls (a), waits for it to finish and then yield something.

// saga A -> action_a
function *saga_a(action) {
  yield put( ...action1...);
  yield call(api, ...params);
  yield put( ...action2...);
}


// saga B -> action_b
function *saga_b(action) {
  yield put(..action3..)

  waitFor -- put(action_a)     <------ how to achieve this?

  yield put(..action4..)
 }

Answer 1

Yes, there is. You can use take to achieve this.

function *saga_b(action) {
  ...

  yield take('action_a') // this will put the saga_b essentially on hold until `action_a` is handled by the reducer

  ...
}

UPDATE

You can use saga-toolkit in order to put and wait for actions without take-ing them:

const resultOfFetchSomething = yield putAsync(fetchSomething()) // dispatches action "fetchSomething" & wait for the saga that is attached to it to finish running

Answer 2

The way I do it my code bases is by calling the other saga directly. It unfortunately couples the two together, but since you need to wait the coupling will at least be more explicit.

function *saga_b(action) {
  yield put(..action3..)
  yield call(saga_a, action_a)
  yield put(..action4..)
}