Evolution of Sense ActionCreators

sense-action-creator-1.js

const getUser = (userId) => (dispatch, getState) => {
  // check if we are currently fetching and return that promise
  const fetching = getState().fetching[userId];
  if (fetching) {
    return fetching;
  }
  
  // check if the user is cached
  const cacheItem = getState().cache[userId];
  if (cacheItem && cacheItem.expireTime > Date.now()) {
    return;
  }

  // initiate the request
  const promise = api.get(`/user/${userId}`).then(user => {
    // populate the store with the received data
    dispatch(receiveUser(user));

    // tell components that we have stopped fetching
    dispatch(stopFetchingUser(userId, promise));
  }, () => {

    // do the same for the error case
    dispatch(stopFetchingUser(userId, promise));
  });

  // let components know we are fetching this data
  dispatch(startFetchingUser(userId, promise));

  return promise;
};