get the ID of collection document from Firestore using Angularfire2 in ionic 3 [duplicate]

Answer 1

i changed the code to:

  this.itemsCollection = this.afs.collection('posts', ref => ref.orderBy('createdDate', 'desc'));
  this.items = this.itemsCollection.snapshotChanges().pipe(
    map(actions => actions.map(a => {
      const data = a.payload.doc.data() as Item;
      const id = a.payload.doc.id;
      return { id, ...data };
    }))
  );

and it worked perfectly.