使用"this“绑定的验证器将FromGroup显示为未定义

import { Component, OnInit } from '@angular/core';
import { FormGroup, FormControl, Validators } from '@angular/forms';

@Component({
  selector: 'app-my-form',
  templateUrl: './my-form.component.html',
  styleUrls: ['./my-form.component.css']
})
export class MyFormComponent implements OnInit {
  myForm: FormGroup;

  constructor() { }

  ngOnInit() {
    this.myForm = new FormGroup({
      username: new FormControl('', Validators.required),
      password: new FormControl('', Validators.minLength(6))
    });

    // 使用bind()方法将"this"关键字绑定到正确的上下文中
    this.myForm.setValidators(this.customValidator.bind(this));
  }

  customValidator(form: FormGroup) {
    if (form.get('username').value === 'admin' && form.get('password').value === 'password') {
      return null; // 验证通过
    } else {
      return { invalidCredentials: true }; // 验证失败
    }
  }
}