"Type 'ValidatorFn | null' is not assignable to type 'ValidatorFn'." angular 中的联系表单组件

Question

我正在尝试在 Angular 中创建一个联系表单，但我在我的联系人 form.ts 中收到一个我无法理解的错误。这是我的代码：

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

@Component({
  selector: 'app-contact-form',
  templateUrl: './contact-form.component.html',
  styleUrls: ['./contact-form.component.css']
})
export class ContactFormComponent implements OnInit {

  FormData: FormGroup | undefined;

  constructor(private builder: FormBuilder) { }

  ngOnInit(): void {
    this.FormData = this.builder.group ({
      Fullname: new FormControl('', [Validators.required]),
      Email: new FormControl('', [Validators.compose([Validators.required, Validators.email])]),
      Comment: new FormControl ('', [Validators.required])
    })
  }
}

给我带来麻烦的行如下：

Email: new FormControl('', [Validators.compose([Validators.required, Validators.email])])

我被告知

Type 'ValidatorFn | null' is not assignable to type 'ValidatorFn'.
Type 'null' is not assignable to type 'ValidatorFn'.ts(2322)

谢谢！

Answer 1

Validators.compose() 将 return ValidatorFn 或 null 的值。

static compose(validators: null): null

您在 tsconfig.json 中启用严格类型检查 (strict: true) 时遇到此错误。

会说您不需要使用 Validators.compose()，而是使用 数组 (ValidatorFn[]) 进行多项验证检查，如下所示：

this.FormData = this.builder.group ({
  Email: new FormControl('', [Validators.required, Validators.email]),
  ...
})

Sample Demo on StackBlitz

"Type 'ValidatorFn | null' is not assignable to type 'ValidatorFn'." angular 中的联系表单组件

"Type 'ValidatorFn | null' is not assignable to type 'ValidatorFn'." contact-form component in angular

html

validation

typescript

angular

angular-reactive-forms