I have an implementation where parent wants to pass certain data to child component via the use of @Input
parameter available at the child component. However, this data transfer is a optional thing and the parent may or may not pass it as per the requirement. Is it possible to have optional input parameters in a component. I have described a scenario below:
<parent>
<child [showName]="true"></child> //passing parameter
<child></child> //not willing to passing any parameter
</parent>
//child component definition
@Component {
selector:'app-child',
template:`<h1>Hi Children!</h1>
<span *ngIf="showName">Alex!</span>`
}
export class child {
@Input showName: boolean;
constructor() { }
}
You can use the ( ? ) operator as below
import {Component,Input} from '@angular/core';
@Component({
selector:'child',
template:`<h1>Hi Children!</h1>
<span *ngIf="showName">Alex!</span>`
})
export class ChildComponent {
@Input() showName?: boolean;
constructor() { }
}
The parent component that uses the child component will be as
@Component({
selector: 'my-app',
template: `
<div>
<h2>Hello {{name}}</h2>
<child [showName]="true"></child>
<child ></child>
</div>
`,
})
export class App {
name:string;
constructor() {
this.name = 'Angular2'
}
}