javascript - Angular 2: View not updating on array push - Stack Overflow

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I have two child ponents. 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 ponent 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 ponent. 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);
}

I have two child ponents. 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 ponent 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 ponent. 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);
}

• javascript
• arrays
• angular
• typescript

Share Improve this question Follow edited Jan 23, 2017 at 20:18 LadyT asked Jan 23, 2017 at 18:48 LadyTLadyT 65922 gold badges1212 silver badges3232 bronze badges 17

• 1 Can you show us the ponent code? What you posted looks correct; the problem might be elsewhere. – chrispy Commented Jan 23, 2017 at 18:55
• 1 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 Commented Jan 23, 2017 at 19:09
• 1 @SteveG. I added the code that I am using. A display ponent to display the data, and a button to push data into the array. – LadyT Commented Jan 23, 2017 at 20:19
• 2 ngFor iterates over items not data – Günter Zöchbauer Commented Jan 23, 2017 at 20:49
• 4 Possible duplicate of Why angular 2 ngOnChanges not responding to input array push – crh225 Commented Mar 15, 2018 at 15:20

 |  Show 12 more ments

1 Answer 1

Sorted by: Reset to default 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];
}

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