Angular: Passing down data using @Input()

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I have three component-- Component A, Component B and Component C. Component A wraps Component B. Component B wraps Component C. If I use @Input() in each component, will changes to options in the root component pass through the nested components to Component C? See below:

<component-a [options]="options">
  <component-b [options]="options">
    <component-c [options]="options">
    </component-c>
  </component-b>
</component-a>

I asked this question because when options changes in the root component of the application I need to do some filtering at each nested component. However, I have noticed some unusual behavior with a third-party component that doesn't seem to receive options? I can elaborate further after the first part of this question is answered.

I believe the answer to the question is "Yes". So here is the second part. How do I update <ng-select> when the components are wraps as follows:

<component-a [options]="options">
  <component-b [options]="options">
    <ng-select [items]="options" [(ngModel)]="selectedOption">
    </ng-select>
  </component-b>
</component-a>

When the documentation for <ng-select> says the following:

Change Detection

Ng-select component implements OnPush change detection which means the dirty checking checks for immutable data types. That means if you do object mutations like:

this.items.push({id: 1, name: 'New item'})

Component will not detect a change. Instead you need to do:

this.items = [...this.items, {id: 1, name: 'New item'}];

This will cause the component to detect the change and update. Some might have concerns that this is a pricey operation, however, it is much more performant than running ngDoCheck and constantly diffing the array.

So how do I ensure changes to options is reflected in <ng-select>?

I have a workaround. Since your options is a object , angular won't detect changes to the object. You need to change the reference of the object in order for angular to detech the changes

Below is the code that will work and you change detection will be as expected

this.options = Object.assign({},this.options)

The above code will change the reference of the object due to which change detection will be triggered

Passing data into Angular components with @Input, This is done via “input” binding to pass data from one component to another This custom input binding is created via the @Input() decorator! we can set some initial data to be delegated down into our CounterComponent . The first step to passing data into an Angular component is to create a custom property to bind to. This is done via “input” binding to pass data from one component to another (typically parent to child). This custom input binding is created via the @Input() decorator!

Yes, you can pass @Input parameters down through multiple components in this way. I don't know the answer to your question about ng-select, however in the component.ts file you can use the ngOnChanges lifecycle hook to detect when an @Input value has changed. Here is a decent article about it: https://ngdev.space/angular-2-input-property-changes-detection-3ccbf7e366d2

Component interaction, Pass data from parent to child with input bindinglink 'Master'; it('should pass properties to children properly', function () { let parent = element.all(by. In Angular, you can pass data from a parent component to a child component using the @Input() decorator, and a child component can emit an event to a parent component using the @Output() decorator.

Ultimately, I decided to use <ng-option> template and *ngFor although I do like @renil-babu way to mutate.

<ng-select [id]="name"
           [attr.name]="name"
           [placeholder]="placeholder">
    <ng-option *ngFor="let input of options" [value]="input.value">
        {{ input.text }}
    </ng-option>
</ng-select>

Update: Unfortunately, this will not work since the the variable that is passed down isn't honored when options change

The final implementation requires immutability and (add) event to trigger it.

<ng-select
  [items]="items"
  [multiple]="true"
  (add)="exclude($event, items)" 
  [(ngModel)]="selected">
</ng-select>
<br>
<ng-select
  [items]="items2"
  [multiple]="true" 
  (add)="exclude($event, items2)" 
  [(ngModel)]="selected2">
</ng-select>
<br>
<ng-select
  [items]="items3"
  [multiple]="true" 
  (add)="exclude($event, items3)" 
  [(ngModel)]="selected3">
</ng-select>

And here is the Typescript:

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

@Component({
  selector: 'my-app',
  templateUrl: './app.component.html',
  styleUrls: [ './app.component.css' ]
})
export class AppComponent  {

  selected;
  selected2;
  selected3;

  items: string[];
  items2: string[];
  items3: string[];

  all :any[];

  ngOnInit() {
    this.items = ['Vilnius', 'Kaunas', 'Klaipeda'];
    this.items2 = [...this.items];
    this.items3 = [...this.items];

    this.all = [this.items, this.items2, this.items3];
  }

  exclude(item, currentArray) {
    for (let i = 0; i < 3; i++) {
      const items = this.all[i];
      if (items !== currentArray) {
        this.all[i] = items.filter(x => x !== item);
      }
    }
    this.items = this.all[0];
    this.items2 = this.all[1];
    this.items3 = this.all[2];
  }
}

Passing Data to a Nested Component with @Input, In this guide, we are going to learn about @Input() . One of the most useful decorators in Angular, it sends data over to the component and No more code is required on the parent side to send the data from parent to child. So, Angular events can be treated like regular HTML DOM based events when it comes to cancellable event propagation. The @Input() decorator defines a set of parameters that can be passed down from the component's parent.

Communication Between Components Using Input and Output , Passing Data from Parent to Child Component with Input Binding As we can see in the below example, we must import Input from '@angular/core' library. Intercepting Input Property Changes with a Setter and ngOnChanges() will get increased and when we click on the button 'New maximum value',  Angular's unidirectional data flow rule prevents updating the parent view's in the same cycle. The app has to wait one turn before it can display the seconds. Use setTimeout () to wait one tick and then revise the seconds () method so that it takes future values from the timer component.

Angular: Passing down data using @Input() · Issue #742 · ng-select , Angular: Passing down data using @Input() #742 options in the root component pass through the nested components to Component C? See  Get user input from a template reference variablelink. There's another way to get the user data: use Angular template reference variables. These variables provide direct access to an element from within the template. To declare a template reference variable, precede an identifier with a hash (or pound) character (#).

Passing Data into a Component, The @Input() decorator defines a set of parameters that can be passed down from the component's parent. For example, we can modify the HelloComponent  1. Using @input decorator : In order use, @input decorator we first need to include Input from @angular/corelibrary, as shown below. import { Input } from '@angular/core'; Now let’s use @input decorator, to receive data from parent controller, In order to do that we will use the key written insidesquareBrackets ([ ]) in parent controller.