saga-with-selector.js

import { call, put, select, takeEvery } from 'redux-saga/effects';

import {
  API_BUTTON_CLICK,
  API_BUTTON_CLICK_SUCCESS,
  API_BUTTON_CLICK_ERROR,
} from './actions/consts';
import { getDataFromAPI } from './api';
import { getUserAccessToken } from './selectors';

export function* apiSideEffect(action) {
  try {
    const accessToken = yield select(getUserAccessToken);
      
    if (!accessToken) {
      throw new Error('No access token - aborting');
    }

    const data = yield call(getDataFromAPI, accessToken);
    yield put({ type: API_BUTTON_CLICK_SUCCESS, payload: data });
  } catch (e) {
    yield put({ type: API_BUTTON_CLICK_ERROR, payload: e });
  }
}

// the 'watcher' - on every 'API_BUTTON_CLICK' action, run our side effect
export function* apiSaga() {
  yield takeEvery(API_BUTTON_CLICK, apiSideEffect);
}