如何在angular7中减少反应式表单验证的代码

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

@Component({
  selector: 'app-reactive-form',
  templateUrl: './reactive-form.component.html',
  styleUrls: ['./reactive-form.component.css']
})
export class ReactiveFormComponent {
  form: FormGroup;

  constructor(private fb: FormBuilder) {
    this.form = this.fb.group({
      name: ['', Validators.required],
      email: ['', [Validators.required, Validators.email]],
      password: ['', [Validators.required, Validators.minLength(6)]]
    });
  }

  onSubmit() {
    if (this.form.valid) {
      console.log(this.form.value);
    }
  }
}

import { AbstractControl, ValidatorFn } from '@angular/forms';

export function forbiddenNameValidator(nameRe: RegExp): ValidatorFn {
  return (control: AbstractControl): { [key: string]: any } | null => {
    const forbidden = nameRe.test(control.value);
    return forbidden ? {'forbiddenName': {value: control.value}} : null;
  };
}

this.form = this.fb.group({
  username: ['', [Validators.required, forbiddenNameValidator(/admin/i)]]
});

<form [formGroup]="form" (ngSubmit)="onSubmit()">
  <input formControlName="email" type="email">
  <div *ngIf="form.get('email').invalid && (form.get('email').dirty || form.get('email').touched)">
    <div *ngIf="form.get('email').errors.required">Email is required.</div>
    <div *ngIf="form.get('email').errors.email">Email is invalid.</div>
  </div>
  <button type="submit" [disabled]="form.invalid">Submit</button>
</form>