Dev Notes Blog

Signal inputs let you get values from parent components. These values are shown using a Signal

Optional inputs: Inputs are optional by default unless you use input.required. You can provide an initial value, or Angular will use undefined by default.
Required inputs: Required inputs must always have a value of the specified input type. They are defined using the input.required function.

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import { Component, InputSignal, input } from '@angular/core';
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@Component({
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  selector: 'app-root',
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  standalone: true,
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  template: `<div>
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    <p>Counter Value: {{ counter }}</p>
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    <p>Counter Value: {{ counter() }}</p>
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    <p>UserName Value: {{ userName }}</p>
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    <p>UserName Value: {{ userName() }}</p>
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    <p>LastName Value: {{ lastName }}</p>
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    <p>LastName Value: {{ lastName() }}</p>
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  </div>`,
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})
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export class AppComponent {
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  @Input() counter: number | undefined;
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  counter: InputSignal<number | undefined> = input<number>();
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  @Input({ required: true }) userName!: string;
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  userName: InputSignal<string> = input.required<string>();
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  @Input() lastName: string = 'arias';
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  lastName: InputSignal<string> = input<string>('arias');
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}

Input Alias

Angular uses the class member name as the input name by default. However, you can alias inputs to give them a different public name.

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import { Component, InputSignal, input } from '@angular/core';
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@Component(/** ... */)
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export class AppComponent {
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  name: InputSignal<string> = input<string>('andres', { alias: 'userName' });
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}

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<app-component [userName]="value" />

Angular Signal Input

Input Alias