How to reference an array from one component to another in Angular 2

Within my AddUserComponent, I have a public array declared like this:

public arr: Array<any> = [] 

This array stores the names of users. Now, I need to access these values in another component called AddTopicComponent in order to display the user's names as a dropdown menu. However, these two components are not directly related as parent-child components. How can I achieve this?

Answer №1

To pass data from a container component to inner components, you can utilize the @Input decorator. Here is a helpful resource for further explanation: https://angular.io/guide/attribute-directives#pass-values-into-the-directive-with-an-input-data-binding

If the components do not have a parent-child relationship, consider using one of the following approaches:

  • Utilizing Services (Highly Recommended).
  • Implementing Behavior Subjects from the RxJS library.
  • Using browser storage (session/local), although this is the least recommended option due to data security risks.

Answer №2

Here is an example showcasing the interaction between parent and child components in Angular.

  1. Parent to child binding is achieved through property binding, where a master string is passed to the child component using a custom property called childToMaster with @Input decorator.
  2. Child to parent binding is implemented via event binding using @Output decorator. Look for the childToMaster event.

See the working demo here

Parent Component:

import { Component, Output, EventEmitter } from '@angular/core';

@Component({
  selector: 'my-app',
  templateUrl: './app.component.html',
  styleUrls: [ './app.component.css' ]
})
export class AppComponent  {
  // Passing values from parent to child
  master: string = "sent from parent";

  // Receiving value from child
  childToParent(name) {
    this.master = name;
  }
}

Parent Template:

<div>
  <span>Master to Child </span><input type="text" [(ngModel)]='master'>
</div>

<app-child [childToMaster]=master (childToParent)="childToParent($event)"></app-child>

Child Component with Template:

import { Component, Input, Output, EventEmitter } from '@angular/core';

@Component({
  selector: 'app-child',
  template: `
    <input type="text" [(ngModel)]='masterName'>
    <button (click)="sendToParent(masterName)">Send to Parent</button>
    <div>{{masterName}}</div>
  `
})
export class AppChildComponent {
  // Receiving value from parent to child
  @Input('childToMaster') masterName: string;
  
  @Output() childToParent = new EventEmitter<String>();

  sendToParent(name) {
    this.childToParent.emit(name);
  }
}

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