RangeError:使用 valueChanges.subscribe 时超出了最大调用堆栈大小

问题描述

我将 Angular 5 与 Reactive 表单一起使用，需要利用 valueChanges 来动态禁用所需的验证

I am using Angular 5 with Reactive forms and need to make use of the valueChanges in order to disable required validation dynamically

组件类:

export class UserEditor implements OnInit {

    public userForm: FormGroup;
    userName: FormControl;
    firstName: FormControl;
    lastName: FormControl;
    email: FormControl;
    loginTypeId: FormControl;
    password: FormControl;
    confirmPassword: FormControl;
...

ngOnInit() {
    this.createFormControls();
    this.createForm();
    this.userForm.get('loginTypeId').valueChanges.subscribe(

            (loginTypeId: string) => {
                console.log("log this!");
                if (loginTypeId === "1") {
                    console.log("disable validators");
                    Validators.pattern('^[0-9]{5}(?:-[0-9]{4})?$')]);
                    this.userForm.get('password').setValidators([]);
                    this.userForm.get('confirmPassword').setValidators([]);

                } else if (loginTypeId === '2') {
                    console.log("enable validators");
                    this.userForm.get('password').setValidators([Validators.required, Validators.minLength(8)]);
                    this.userForm.get('confirmPassword').setValidators([Validators.required, Validators.minLength(8)]);

                }

                this.userForm.get('loginTypeId').updateValueAndValidity();

            }

        )
}
createFormControls() {
    this.userName = new FormControl('', [
        Validators.required,
        Validators.minLength(4)
    ]);
    this.firstName = new FormControl('', Validators.required);
    this.lastName = new FormControl('', Validators.required);
    this.email = new FormControl('', [
      Validators.required,
      Validators.pattern("[^ @]*@[^ @]*")
    ]);
    this.password = new FormControl('', [
       Validators.required,
       Validators.minLength(8)
    ]);
    this.confirmPassword = new FormControl('', [
        Validators.required,
        Validators.minLength(8)
    ]);

}

createForm() {
 this.userForm = new FormGroup({
      userName: this.userName,
      name: new FormGroup({
        firstName: this.firstName,
        lastName: this.lastName,
      }),
      email: this.email,
      loginTypeId: this.loginTypeId,
      password: this.password,
      confirmPassword: this.confirmPassword
    });
}

但是，当我运行它时，我收到浏览器 javascript 错误

However when I run it I get a browser javascript error

UserEditor.html:82 ERROR RangeError: Maximum call stack size exceeded
    at SafeSubscriber.tryCatcher (tryCatch.js:9)
    at SafeSubscriber.webpackJsonp.../../../../rxjs/_esm5/Subscription.js.Subscription.unsubscribe (Subscription.js:68)
    at SafeSubscriber.webpackJsonp.../../../../rxjs/_esm5/Subscriber.js.Subscriber.unsubscribe (Subscriber.js:124)
    at SafeSubscriber.webpackJsonp.../../../../rxjs/_esm5/Subscriber.js.SafeSubscriber.__tryOrUnsub (Subscriber.js:242)
    at SafeSubscriber.webpackJsonp.../../../../rxjs/_esm5/Subscriber.js.SafeSubscriber.next (Subscriber.js:186)
    at Subscriber.webpackJsonp.../../../../rxjs/_esm5/Subscriber.js.Subscriber._next (Subscriber.js:127)
    at Subscriber.webpackJsonp.../../../../rxjs/_esm5/Subscriber.js.Subscriber.next (Subscriber.js:91)
    at EventEmitter.webpackJsonp.../../../../rxjs/_esm5/Subject.js.Subject.next (Subject.js:56)
    at EventEmitter.webpackJsonp.../../../core/esm5/core.js.EventEmitter.emit (core.js:4319)
    at FormControl.webpackJsonp.../../../forms/esm5/forms.js.AbstractControl.updateValueAndValidity (forms.js:3377)

记录这个！"重复记录调用，就像递归调用一样，这就是为什么它们是堆栈错误

"log this!" is loggedcalled repeatedly like it is called recursively which is why their is a stack error

如果我删除 valueChanges.subscribe 代码除了有条件地删除验证.

If I remove the valueChanges.subscribe the code work apart from removing the validation conditionally.

为什么递归调用 valueChanges.subscribe ?

Why is it calling valueChanges.subscribe recursively?

推荐答案

问题是你在 valueChanges 事件处理程序中为同一字段修改了字段的值，导致事件再次触发:

The problem is that you modify the value of the field inside of the valueChanges event handler for that same field, causing the event to be triggered again:

this.userForm.get('loginTypeId').valueChanges.subscribe(
  (loginTypeId: string) => {
    ...
    this.userForm.get('loginTypeId').updateValueAndValidity(); <-- Triggers valueChanges!
}

这篇关于RangeError:使用 valueChanges.subscribe 时超出了最大调用堆栈大小的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！