Viewport not displaying data received from ts constructor

Issue

I am receiving data in constructor using where condition from Firestore. When I console.log I see my array but it does not reflect on viewport home.html till I click anywhere on page or change browser window [ like open some other window and come back to this window].

My friend guided me to use ChangeDetectorRef and I used it as guided by her. I have called this.cd.detectChanges(); when all of the data is fetched any my array is ready, but it did not work.

Below is my code::

home.ts

import { Component, OnInit } from "@angular/core";
import * as firebase from "firebase";
import { firestore } from "firebase/app";
import {
  AngularFirestoreCollection,
  AngularFirestore,
} from "@angular/fire/firestore";
import { ChangeDetectorRef } from "@angular/core";

@Component({
  selector: "app-test1",
  templateUrl: "./test1.page.html",
  styleUrls: ["./test1.page.scss"],
})
export class Test1Page implements OnInit {
  dailyreports: any = [];
  constructor(
    private firestore: AngularFirestore,
    private cd: ChangeDetectorRef
  ) {
    let start = new Date("2020-03-29");
    firebase
      .firestore()
      .collection("dailyreport")
      .where("timestamp", ">=", start)
      .onSnapshot((querySnapshot) => {
        querySnapshot.forEach((doc) => {
          console.log(doc.id, " ===> ", doc.data());
          this.dailyreports.push(doc.data());
        });
        this.cd.detectChanges();
        console.log(this.dailyreports);
      });
  }

  ngOnInit() {}
}

home.html

<ion-content>
  <div
    class="info col-11"
    *ngFor="let list of this.dailyreports; let i = index;"
    (click)="openModaWithData(i)"
  >
    <div id="chtv">
      Click here to view what {{list.name}} did.
    </div>

    <div id="rcorners">
      {{list.name}}
    </div>

    <div id="rcorners2">
      {{list.timestamp}}
    </div>
    <br />
  </div>
</ion-content>

Solution

You can force angular to refresh (change-detection) based on variable re-assignment.

firebase
  .firestore()
  .collection("dailyreport")
  .where("timestamp", ">=", start)
  .onSnapshot((querySnapshot) => {
    // Get new items
    const newItems = [];
    querySnapshot.forEach((doc) => {
      console.log(doc.id, " ===> ", doc.data());
      newItems.push(doc.data());
    });
    console.log({ newItems });
    // Trigger change detection
    this.dailyreports = this.dailyreports.concat(newItems)
  });

Answered By - Ben Winding