无法实现 ValidatorFn 接口

Question

我想使用 Angular 的接口实现自定义跨字段验证器ValidatorFn。

这是我的代码：（我按照https://angular.io/guide/form-validation#cross-field-validation上提供的步骤进行操作）

import { ValidatorFn, ValidationErrors, FormGroup } from "@angular/forms";

/**
* This validator implements the ValidatorFn Interface from Angular. 
* 
* @param formGroup- the FormGroup that needs Validation
* 
* @returns null if the form is valid, else some {@link ValidatorErrors}
*/
export const CompleteBloodpressureValidator: ValidatorFn = (formGroup: FormGroup) => {

    const bloodpressureSys = formGroup.get("bloodPressureSysFormControl");
    const bloodpressureDia = formGroup.get("bloodPressureDiaFormControl");

    if (bloodpressureSys != null && bloodpressureDia == null || bloodpressureSys == null && bloodpressureDia != null){
        // return some custom ValidatorErrors
        return {
            bloodPressureIncomplete: true
        };
    }
    // if everything is fine, return null
    return null;
 }

但角度编译器不断告诉我以下内容：

Type '(fromGroup: FormGroup) => { bloodPressureIncomplete: boolean; } | null' is not assignable to type 'ValidatorFn'.

Types of parameters 'fromGroup' and 'control' are incompatible.

Type 'AbstractControl' is missing the following properties from type 'FormGroup': controls, registerControl, addControl, removeControl, and 3 more.ts(2322)

在我看来这没有任何意义，我的实现ValidatorFn正是它应该的样子。

有什么建议我在这里做错了什么吗？

Answer 1

So the answer to this question is to update the TypeScript version or exchange

formGroup: FormGroup

with

formGroup: AbstractControl

It seems to be caused by a bug in the TypeScript version.

编辑：更新到最新的 TypeScript 版本不会改变任何内容。我想这可能是 Angular 文档中的一个错误。