reducer_with_states.ts

export interface ResultState {
  result: Result|null,
  callState: CallState;
}

const initState: ResultState = {
  result: null,
  callState: LoadingState.INIT,
}

export function reducer(state: ResultState = initState, action: actions.All): ResultState {
  switch(action.type) {
    case actions.FETCH_RESULT: {
      return {
        ...state,
        // set to loading
        callState: LoadingState.LOADING,
      };
    }
    case actions.FETCH_RESULT_SUCCESS: {
      return {
        ...state,
        result: action.result;
        callState: LoadingState.LOADED,
      };
    }
    case actions.FETCH_RESULT_ERROR: {
      return {
        ...state,
        callState: {error: action.errorMsg},
      };
    }
    case default: {
      return state; // return state untouched
    }
  }
}