Firestore + AngularFire2 pagination ( query items by range - .startAfter(lastVisible) )

Question

In a component I want to pull a range of items from FireStore, for ex. from 0 to 5, from 5 to 10 etc. I found this in FireStore\'s docs, but they dont use AngularFire2 so as

Answer 1

Source Tutorial Link

AngularFire2 used for FireStore database operations

using below methods:

For Next Page

    nextPage() {
      this.disable_next = true;
      this.firestore.collection('People', ref => ref
        .limit(5)
        .orderBy('timestamp', 'desc')
        .startAfter(this.lastInResponse)
      ).get()
        .subscribe(response => {

          if (!response.docs.length) {
            this.disable_next = true;
            return;
          }

          this.firstInResponse = response.docs[0];

          this.lastInResponse = response.docs[response.docs.length - 1];
          this.tableData = [];
          for (let item of response.docs) {
            this.tableData.push(item.data());
          }

          this.pagination_clicked_count++;

          this.push_prev_startAt(this.firstInResponse);

          this.disable_next = false;
        }, error => {
          this.disable_next = false;
        });
    }

For Previous Page

    prevPage() {
      this.disable_prev = true;
      this.firestore.collection('People', ref => ref
        .orderBy('timestamp', 'desc')
        .startAt(this.get_prev_startAt())
        .endBefore(this.firstInResponse)
        .limit(5)
      ).get()
        .subscribe(response => {
          this.firstInResponse = response.docs[0];
          this.lastInResponse = response.docs[response.docs.length - 1];

          this.tableData = [];
          for (let item of response.docs) {
            this.tableData.push(item.data());
          }

          //Maintaing page no.
          this.pagination_clicked_count--;

          //Pop not required value in array
          this.pop_prev_startAt(this.firstInResponse);

          //Enable buttons again
          this.disable_prev = false;
          this.disable_next = false;
        }, error => {
          this.disable_prev = false;
        });
    }

Check complete tutorial and demo on this link