Angular 2: View not updating on array push

Question

I have two child components. They are sharing data from a json file that I am loading using the http.get/subscribe method. For some reason, when I push data into the array, it doesnt update in the view. It shows the updated array in the console though.

app component loading the data from a service

this.dataService.getData()
 .subscribe(
     data => {
       this.data = data;
     },
     (err) => console.log('Error: ', err),
     () => console.log("success!")
   );

I am using inputs to access the data in my child component. Are there any ways in Angular 2 to update the view when new values are pushed into the array.

Display Component

<div *ngFor="let i of items; let k = index"><h1>{{i.title}}</h1> <p>{{i.desc}}</p></div>

The Button Component

<button (click)="addItem(i)">Add Item</button>

The Component Function
addItem(i){
  let data = {title: "Some title", desc: "Some desc"};
  this.data.list[i].items.push(data);
}

Can you show us the component code? What you posted looks correct; the problem might be elsewhere. — chrispy
– chrispy, Commented Jan 23, 2017 at 18:55
are you using the OnChanges lifecycle hook? You might need to call that if you're doing some more work on the update to "data" :) — chrispy
– chrispy, Commented Jan 23, 2017 at 19:09
@SteveG. I added the code that I am using. A display component to display the data, and a button to push data into the array. — LadyT
– LadyT, Commented Jan 23, 2017 at 20:19
Possible duplicate of Why angular 2 ngOnChanges not responding to input array push — crh225
– crh225, Commented Mar 15, 2018 at 15:20

David Sajdl · Accepted Answer · 2019-10-16 09:00:35Z

12

I have the same problem and I solved this by using spread operator to create a new array of the object rather than to push new element into an existing array.

in your case I would do something like:

addItem(i){
  let data = {title: "Some title", desc: "Some desc"};
  this.data.list[i].items = [...this.data.list[i].items, data];
}

answered Oct 16, 2019 at 9:00

David Sajdl

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1 Comment

Ahmad Alkhatib Over a year ago

isn't that the same idea of "concat" ?

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