Updating the variable in Angular 6 does not cause the view to refresh

Question

Updating the variable in Angular 6 does not cause the view to refresh

I am facing an issue with my array variable that contains objects. Here is an example of how it looks:

[{name: 'Name 1', price: '10$'}, {name: 'Name 2', price: '20$'}, ...]

In my view, I have a list of products being printed out like this:

<div *ngFor="let item of items">
   {{item.name}} - {{item.price}}
</div>

Even if I change the 'items' array in the code due to an external event, the variable updates but the view does not refresh.

How can I resolve this issue?

Edit:

The function changeArray() only consists of one line:

changeArray(items) : void{
    this.items = items;
}

I suspect that the problem lies in calling this method from another component. For instance, in component 'B', I have a line similar to this:

a.changeArray(items);

javascript angular typescript binding

Answer 1

Answer №1

If you need to refresh the list, one method is to utilize the spread operator ...

After updating the property (e.g., items) in your component, follow these steps:

// Assume items is an array and update logic has been completed,
this.items = [...this.items];

This action should effectively refresh your list.

For a more customized solution, it's helpful if you can provide the full code showcasing the issue.

UPDATE:

In response to your feedback,

Revise the changeArray() function as shown below:

changeArray(items) : void{
  this.items = [...items];
}

UPDATE2:

If the previous step doesn't yield results, consider adding the following lines to the constructor of the component where changeArray() is located. Make sure to import ChangeDetectorRef as well:

import { ChangeDetectorRef } from '@angular/core';

constructor(cRef: ChangeDetectorRef) {}

changeArray(items) : void{
  this.items = [...items];
  this.cRef.detectChanges();
}

Hopefully, this approach resolves the issue.

Answer 2

If you need to refresh the list, one method is to utilize the spread operator ...

After updating the property (e.g., items) in your component, follow these steps:

// Assume items is an array and update logic has been completed,
this.items = [...this.items];

This action should effectively refresh your list.

For a more customized solution, it's helpful if you can provide the full code showcasing the issue.

UPDATE:

In response to your feedback,

Revise the changeArray() function as shown below:

changeArray(items) : void{
  this.items = [...items];
}

UPDATE2:

If the previous step doesn't yield results, consider adding the following lines to the constructor of the component where changeArray() is located. Make sure to import ChangeDetectorRef as well:

import { ChangeDetectorRef } from '@angular/core';

constructor(cRef: ChangeDetectorRef) {}

changeArray(items) : void{
  this.items = [...items];
  this.cRef.detectChanges();
}

Hopefully, this approach resolves the issue.

Answer 3

Answer №2

When working with Angular, it is essential to remember that arrays should be treated as immutable objects. This means that you should avoid altering the contents of an array directly, and instead create a new array when making changes (updating the reference).

For instance, consider using the concat method to add elements to an array, rather than using the push method which modifies the original array.

Answer 4

When working with Angular, it is essential to remember that arrays should be treated as immutable objects. This means that you should avoid altering the contents of an array directly, and instead create a new array when making changes (updating the reference).

For instance, consider using the concat method to add elements to an array, rather than using the push method which modifies the original array.

Updating the variable in Angular 6 does not cause the view to refresh

Answer №1

Answer №2

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