无法在我的 angular4 代码中将 Observable Array 组合为空 Observable 数组

Question

我使用 angular 4 和 angularfire2 编写了一个组件，但我得到一个错误的回报，说 “ERROR TypeError: _this.memberEvents$.combineLatest is not a function”。

请参考以下代码并指出纠正方法。

    import { Observable } from 'rxjs/Observable';
    import { MemberService } from './../../member.service';
    import { ClubService } from './../../club.service';
    import { ActivatedRoute } from '@angular/router';
    import { EventService } from './../../event.service';
    import { Component, OnInit, OnChanges, OnDestroy } from '@angular/core';
    import { select } from 'ng2-redux';
    import 'rxjs/add/operator/take';
    import 'rxjs/add/operator/map';
    import 'rxjs/add/operator/mergeMap';
    import 'rxjs/add/observable/empty' 
    import 'rxjs/add/operator/takeUntil';
    import 'rxjs/add/observable/combineLatest';
    import 'rxjs/add/observable/of';
    import { Subject } from 'rxjs';

    @Component({
      selector: 'member-favorite',
      templateUrl: './member-favorite.component.html',
      styleUrls: ['./member-favorite.component.css']
    })
    export class MemberFavoriteComponent implements OnInit, OnDestroy {
      userId;
      favoriteEvents$;
      memberEvents$ = Observable.of([]);
      id;
      private ngClubsUnsubscribe$ = new Subject();

      constructor(private route: ActivatedRoute,
        private eventService: EventService, 
        private clubService: ClubService,
        private memberService: MemberService) {
        this.userId = localStorage.getItem('userId');
        this.id = this.route.snapshot.paramMap.get('id');

      }

      ngOnInit() {
        this.getMemberEvents();
      }

      ngOnDestroy() {
        this.ngClubsUnsubscribe$.next();
        this.ngClubsUnsubscribe$.complete();
      }

      getMemberEvents() {
        this.clubService.getActiveClubs().takeUntil(this.ngClubsUnsubscribe$)
          .subscribe(clubs => {
            clubs.map(c => {
              this.memberService.isMember(c.id, this.userId)
              .take(1)
              .subscribe(res => {
                if(res && res === true) {
                  console.log("user is a member of club ", c.clubname);

                  let clubEvents = this.eventService.getForthCommingEventsOfClub(c.id);
                  this.memberEvents$.combineLatest(clubEvents); 

如何更正这条线。 有没有其他方法可以做到这一点。

                }
              });
            });
          });
      }

    }

Answer 1

您直接从Observable 调用 combineLatest。

例如：Observable.combineLatest(..., ...)。

如果您想添加另一个流，根据您的示例，您可以使用withLatestFrom 运算符：

this.memberEvents$.withLatestFrom(clubEvents);