return subject from inside map

问题

Asking this as a followup on this (How to return observable from subscribe), as the accepted solution didn't solve my use case Here is my code

  @Effect()
  searchQuery$ = this.actions$
    .ofType(PlayerSearchActions.SEARCH_NEW_QUERY)
    .map(toPayload)
    .withLatestFrom(this.store)
    .map((latest: any[]) => latest[1])
    .do((res)=>{console.log("Starting search with:",res);})
    .switchMap((store: MyState) =>
      this.youtubeSearch.resetPageToken()
      .searchAll(store.search.query, store.search.queryParams)
      .do((res)=>{console.log("Effects all:",res);})
      .map((youtubeResponse) => this.playerSearchActions.searchResultsReturned(youtubeResponse))
      .do((res)=>{console.log("Effects intermediate",res);})
    ).do((res)=>{console.log("Effects complete",res);});

  searchAll(query: string, params?: any) {
    console.log('entered searchAll');
    let subject = new Subject();
    this.nowChannellist$.map(channels => channels.map(channel => {
      this._apiOptions.channelId = channel.channelId;
      console.log('entered searchAll for channel:',channel.name);
      subject.next(this.search(query, params));
      subject.complete();
      return channel;
    })).do((res) => { console.log('searchAll done', res); });
    return subject;
  }  

  search(query: string, params?: any) {
    //....some code operating on query and params
    return this.http.get('https://www.googleapis.com/youtube/v3/search', _options)
          .map(response => response.json())
  }

The output on console is :

Starting search with: Object {player: Object, nowPlaylist: Object, nowChannellist: Object, user: Object, search: Object…}

entered searchAll

PS: The above works if I call search() directly(which will have one hardcoded channels) instad of searchAll() I am also fine if I can chain multiple calls to search() directly and then merge them as part of @Effect()searchQuery$ itself.

回答1:

I will try to post the answer but I do not have the full requirements so it is kind of guess.

   let nowChannellist$ = new Rx.Observable.of([{channelId:1}, {channelId:2}]);

   nowChannellist$.switchMap(channels => {
     let channels$ = channels.map(channel => {
       return this.search(chanel);
     });
     return Rx.Observable.forkJoin(channels$);
   })
   .subscribe(x=>console.log(x))

来源：https://stackoverflow.com/questions/43381922/return-subject-from-inside-map