gab-social/app/javascript/gabsocial/reducers/groups.js

import {
  GROUP_FETCH_SUCCESS,
  GROUP_FETCH_FAIL,
  GROUPS_FETCH_SUCCESS,
  GROUPS_BY_CATEGORY_FETCH_SUCCESS,
  GROUPS_BY_TAG_FETCH_SUCCESS,
} from '../actions/groups'
import { GROUP_UPDATE_SUCCESS } from '../actions/group_editor'
import { Map as ImmutableMap, fromJS } from 'immutable'

const initialState = ImmutableMap()

const normalizeGroup = (state, group) => state.set(group.id, fromJS(group))

const normalizeGroups = (state, groups) => {
  groups.forEach(group => {
    state = normalizeGroup(state, group)
  })

  return state
}

export default function groups(state = initialState, action) {
  switch(action.type) {
  case GROUP_FETCH_SUCCESS:
  case GROUP_UPDATE_SUCCESS:
    return normalizeGroup(state, action.group)
  case GROUPS_BY_CATEGORY_FETCH_SUCCESS:
  case GROUPS_BY_TAG_FETCH_SUCCESS:
  case GROUPS_FETCH_SUCCESS:
    return normalizeGroups(state, action.groups)
  case GROUP_FETCH_FAIL:
    return state.set(action.groupId, false)
  default:
    return state
  }
}