getState in redux-saga?

Question

I have a store with a list of items. When my app first loads, I need to deserialize the items, as in create some in-memory objects based on the items. The items are stored in my redux store and handled by an itemsReducer.

I'm trying to use redux-saga to handle the deserialization, as a side effect. On first page load, I dispatch an action:

dispatch( deserializeItems() );

My saga is set up simply:

function* deserialize( action ) {
    // How to getState here??
    yield put({ type: 'DESERISLIZE_COMPLETE' });
}

function* mySaga() {
    yield* takeEvery( 'DESERIALIZE', deserialize );
}

In my deserialize saga, where I want to handle the side effect of creating in-memory versions of my items, I need to read the existing data from the store. I'm not sure how to do that here, or if that's a pattern I should even be attempting with redux-saga.

Answer 1

you can use select effect

import {select, ...} from 'redux-saga/effects'

function* deserialize( action ) {
    const state = yield select();
    ....
    yield put({ type: 'DESERIALIZE_COMPLETE' });
}

also you can use it with selectors

const getItems = state => state.items;

function* deserialize( action ) {
    const items = yield select(getItems);
    ....
    yield put({ type: 'DESERIALIZE_COMPLETE' });
}

Answer 2

Select effect does not help us if we in a callback functions, when code flow is not handled by Saga. In this case just pass dispatch and getState to root saga:

store.runSaga(rootSaga, store.dispatch, store.getState)

And the pass parameters to child sagas

export default function* root(dispatch, getState) { yield all([ fork(loginFlow, dispatch, getState), ]) }

And then in watch methods

export default function* watchSomething(dispatch, getState) ...