javascript - 如何实时查询firestore？

Question

因此，通知集合中存储了一个通知对象列表，我的目标是检索早于当前日期时间的所有通知。

所以我的基本查询是:

    return this.db.collection(environment.collection, ref => ref.where('staffRole', '==', staffRole).where('notificationDate', '<=', new Date().getTime()).orderBy('notificationDate', 'desc'))
      .snapshotChanges()
      .pipe(map(snaps => {
        return snaps.map(snap => {
          return <Notification>{
            id: snap.payload.doc.id,
            ...Object.assign({}, snap.payload.doc.data())
          }
        });
      }));

但是 new Date().getTime() 作为固定参数传递，而不是像我预期的那样实时传递。为了克服这个问题，我更改了订阅部分:

interval(1000)
  .pipe(
    map(tick => new Date()),
    share()
  ).subscribe(date => {
    // console.log(date.getTime());
    this.notificationSubscriber !== undefined ? this.notificationSubscriber.unsubscribe() : false;
    this.notificationSubscriber = this.notificationService.getNotifications(getStaffRolevalue(this.staffRole),
      (this.staffRole === 'csa' || 'ops' || 'admin' ? null : this.loggedInStaffId)).subscribe(notifications => {
        this.notifications = notifications;
        const x = this.notificationCount;
        this.notificationCount = notifications.filter(notification => notification.isRead === 0).length;
        const y = this.notificationCount;
        (y - x) === 1? this.playAudio() : false;
      });
  });

我的逻辑是每秒重新订阅可观察的内容。它确实有效，但读取文档的数据库使用量猛增。所以基本上这个逻辑也不能用。

有没有其他方法可以实现我想要的目标。我愿意接受任何建议，即使是关于更改我的界面，只要我实时检索通知即可。

界面:

export interface Notification {
    id: string,
    isRead: number,
    jobNo: number,
    notificationDate: number,
    notificationMessage: string,
    notificationTitle: string,
    notificationType: number,
    receiverId: string,
    staffRole: number
}

Answer 1

我将服务中的查询更改为简单查询:

        return this.db.collection(environment.collection, ref => ref.where('receiverId', '==', staffId))
          .snapshotChanges()
          .pipe(map(snaps => {
            return snaps.map(snap => {
              return <Notification>{
                id: snap.payload.doc.id,
                ...Object.assign({}, snap.payload.doc.data())
              }
            });
          }));

并在订阅时应用了我的所有逻辑:

    this.notificationService.getNotifications(getStaffRolevalue(this.staffRole),
      (this.staffRole === 'csa' || 'ops' || 'admin' ? null : this.loggedInStaffId)).subscribe(notifications => {
        this.timer !== undefined ? this.timer.unsubscribe() : false;
        this.timer = interval(5000)
          .pipe(
            map(tick => new Date()),
            share()
          ).subscribe(date => {
            this.notifications = notifications.filter(notification => notification.notificationDate <= date.getTime()).sort(function (a, b) { return b.notificationDate - a.notificationDate });
            const x = this.notificationCount;
            this.notificationCount = this.notifications.filter(notification => notification.isRead === 0).length;
            const y = this.notificationCount;
            y - x === 1 ? this.playAudio() : false;
          });
      });