@Input之前的角验证器runnng

Question

I have a component that is actually a form control. This separate component takes an input (@Input) and is supposed to pass it to a form validator. The problem is that the form validator runs before the input is defined. So the result is a validator with undefined parameters. What is the solution?? Thanks...

export class InputComponent{

  @Input() min: number; 
  @Input() max: number; 

  formControl: FormControl;

  constructor() {

    this.formControl = new FormControl('', [
      Validators.required,
      CustomValidators.minMaxlength(this.min, this.max)
    ]);

  }

}

Answer 1

In Angular, Component Inputs aren't fully resolved until the ngOnInit lifecycle hook is called. In components, you generally don't want to have much of anything in the constructor and most initialization should be done in the ngOnInit hook or later.

export class InputComponent{

  @Input() min: number; 
  @Input() max: number; 

  formControl: FormControl;

  constructor() {}


 ngOnInit() {
    this.formControl = new FormControl('', [
      Validators.required,
      CustomValidators.minMaxlength(this.min, this.max)
    ]);

  }
}