aretherecookies-mobile/js/streams/PlacesStream.js

// @flow
import { buildPlaceRecord } from '../records/PlaceRecord';
import { Map } from 'immutable';
import FoodItems$ from './FoodItemsStream';
import { getPlaceDetails } from '../apis/PlaceDetailsApi';
import { memoize } from 'ramda';

/**
 * return a promise of a place details object
 * if already requested return existing promise
 * swallow exceptions so as not to break the stream
 */
const safeGetPlaceDetails = memoize(placeId => {
	return getPlaceDetails(placeId).catch(error => {
		console.log(error); // eslint-disable-line no-console
		return {};
	});
});

const uniquePlaceIds$ = FoodItems$.mergeMap(foodItemMap => {
	return foodItemMap.map(foodItem => foodItem.placeId).toArray();
}).distinct();

const placeRecords$ = uniquePlaceIds$.mergeMap(safeGetPlaceDetails).map(buildPlaceRecord);

export default placeRecords$.scan((accMap, place) => {
	return accMap.set(place.id, place);
}, new Map());