Angular 2 Reactive Forms 异步自定义验证抛出“订阅不是函数”

Question

我已经尝试了 [angular2 async validation this.subscribe exception? 答案的所有排列组合，但我仍然遇到异常。

import {AsyncValidatorFn, AbstractControl } from '@angular/forms';
export function userNameShouldBeUnique(): AsyncValidatorFn {
    return (control: AbstractControl): { [key: string]: any } => {
        return new Promise(resolve => {
            setTimeout(() => {
                if (control.value == 'mosh')
                    resolve({ shouldBeUnique: true });
                else
                    resolve(null);
            }, 1000);
        });
    }
}

并在组件中（最后一次尝试）：

this.myForm = this.fb.group({
            username: [
                '',
                Validators.compose([Validators.required, forbiddenNameValidator(/bob/)]),
                Validators.composeAsync([userNameShouldBeUnique])
            ],
            password: ['', Validators.required]
        });

那我做错了什么？谢谢

Answer 1

解决办法是：

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

export function UniqueValidator(): AsyncValidatorFn {
    return (control: AbstractControl): Promise<any> => {
        return new Promise<any>(resolve => {
            setTimeout(() => {
                if (control.value === 'mosh')
                    resolve({ shouldBeUnique: true });
                else
                    resolve(null);
            }, 1000);
        });
    };
};

现在您已经配置好了返回类型。作为自定义验证添加：

username: ['', Validators.required, UniqueValidator()]

刚刚测试过，它可以工作；）