在角度4中将@Input的值用于没有onInit的其他变量

Question

I want to use @Input value to initialize other variable in angular 4

export class test {
  @Input() id: string;

  condition: boolean = (this.id == 'myid') //Getting this.id as undefined
}

Answer 1

Your @Input is first available at ngOnInit . So you can't access it before ngOnInit call.

Answer 2

You can use id variable directly like id instead of this.id inside a class itself. You have to access variable using this only when variable appeared inside function . But eventually this wouldn't help you, since id value will always be undefined .

Ideally you should use this value inside ngOnInit hook which gets fired when component gets initialized and you will see the value passed from the consumer component.

export class test {
  @Input() id: string;
  condition: boolean;

  ngOnInit(){
     this.condition = (this.id == 'myid')
  }
}