Render dynamic array in the view Angular2

Question

I've got a dynamic array which I want to render in the view of a component when some items added / removed inside.

The array is rendered by ngOnInit() method in my App Component (ts) :

import { Component, OnInit } from '@angular/core';
import { CartService } from './cart/cart.service';

import '../style/app.scss';

@Component({
  selector: 'my-app',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.scss'],
})
export class AppComponent {
    cartItems: any;
    image: any;
    item: any;

  constructor(public cartService: CartService) { }

  ngOnInit(){
    this.cartService.cart$.subscribe((val) => {
        console.log(this.cartService.cartArr)//console shows the array properly, but nothing is shown in the view if I remove "console.log"
    });

  }

}

"The view" for the array inside my App Component (html) :

<ul class="cart">
    <li class="cart__item" *ngFor="let item of cartArr">
       ...
    </li>
</ul>

My CartService :

import { Injectable } from '@angular/core';
import { BehaviorSubject } from 'rxjs/BehaviorSubject';


@Injectable()
export class CartService {
    public cart$ = new BehaviorSubject(null);
    public cartArr = [];

   constructor(){ }

   public addToCart(prod) {
       this.cartArr.push(prod);
       this.cart$.next(this.cartArr);
   }
}

So I wonder how to render the array in the Component html and why my code isn't working outside the console?

Answer 1

Update:

As said @TuongLe in comment if you manually subscribe to your observable then you should to call unsubscribe in ngOnDestroy to prevent memory leak.

You can either

1) set array value:

cartItems: any[];

cartSubscription: Subscription;

ngOnInit() {
  this.cartSubscription = this.cartService.cart$.subscribe((val) => {
    this.cartItems = val;
  });
}

ngOnDestroy() {
  this.cartSubscription.unsubscribe();
}

view

*ngFor="let item of cartItems"

or

2) use async pipe like:

*ngFor="let item of cartService.cart$ | async"