Angularfire2 在 snapshotChanges() 中过滤数据

Question

I have the classic function that get all booking in this way

  getAll(startDate: Date, endDate: Date): Observable<Booking[]> {

  return this.db.collection(`hotel/${this.hoteluid}/booking`, ref =>

    ref.where('data_start', '<=', endDate)

  )
  .snapshotChanges().pipe(
    map((actions => actions.map(a => {
      const data = a.payload.doc.data() as Booking;
      const id = a.payload.doc.id;
      return { id, ...data };
    })))
  );
 }

when i try to filter data in this way

.snapshotChanges().pipe(
    map((actions => actions.map(a => {
      const data = a.payload.doc.data() as Booking;
      const id = a.payload.doc.id;
      if(data.num_room == 4)
      return { id, ...data };
    })))
  );

I obtain an error

ERROR TypeError: Cannot read property 'uid_room' of undefined

thanks all

Answer 1

In your map, if num_room is not 4, then it will be undefined no?

Try a rather than use a conditional, I'd suggest a filter for the array in your map:

 .snapshotChanges().pipe(
    map(actions => 
      actions.map(a => {
        const data = a.payload.doc.data() as Booking;
        const id = a.payload.doc.id;
        return { id, ...data };
      }).filter(a =>
        a.num_room == 4
      )
    )
  );