我很好奇我如何取消订阅我的所有订阅.我知道takeWhile()和takeUntil().我觉得takeUntil()对我来说更有用.
as far as I understand,takeWhile() take effects after we get the data. then unsubscribe until the component is destroy.
什么是使用takeUntil()而不使用它的区别.只是.unsubscribe()？
不使用takeUntil()
ngOnInit() {
this.subscriptions = this._membeRSService.getMembers().subscribe(data =>
this.members = data)
}
ngOnDestroy() {
this.subscriptions.unsubscribe();
}
使用takeUntil
private destroyed$: Subject<{}> = new Subject();
ngOnInit() {
this._membeRSService.getMembers().takeUntil(this.destroyed$).subscribe(data
=> this.members = data)
}
ngOnDestroy() {
this.destroyed$.next();
}
also how can I determine If I unsubscribe successfully?
主要区别在于思维方式……以及样板.
如果没有takeUntil,当你的文件大小和代码行增长时,你可能会得到类似的东西：
private subscription1: Subscription;
private subscription2: Subscription;
private subscription3: Subscription;
private subscription4: Subscription;
private subscription5: Subscription;
private subscription6: Subscription;
ngOnInit() {
this.subscription1 = this.service.method().subscribe(...);
this.subscription2 = this.service.method().subscribe(...);
this.subscription3 = this.service.method().subscribe(...);
this.subscription4 = this.service.method().subscribe(...);
this.subscription5 = this.service.method().subscribe(...);
this.subscription6 = this.service.method().subscribe(...);
}
ngOnDestroy() {
this.subscription1.unsubscribe();
this.subscription2.unsubscribe();
this.subscription3.unsubscribe();
this.subscription4.unsubscribe();
this.subscription5.unsubscribe();
this.subscription6.unsubscribe();
}
或者,您可以声明一个订阅数组并推送到它.
两者似乎都不是很方便,如果你最终有很多方法,包含订阅,如果你不滚动到ngOnDestroy,你将无法看到它们是否被取消订阅.
另一方面,使用Subject更具可读性：
private onDestroy$= new Subject<void>();
ngOnInit() {
this.service.method().takeUntil(this.onDestroy$).subscribe(...);
this.service.method().takeUntil(this.onDestroy$).subscribe(...);
this.service.method().takeUntil(this.onDestroy$).subscribe(...);
this.service.method().takeUntil(this.onDestroy$).subscribe(...);
this.service.method().takeUntil(this.onDestroy$).subscribe(...);
this.service.method().takeUntil(this.onDestroy$).subscribe(...);
}
ngOnDestroy() {
this.onDestroy$.next();
this.onDestroy$.complete();
}
即使订阅在整个文件中划分,您也可以检查takeUntil(this.onDestroy $)是否存在.
它也更接近Rxjs和处理流的想法.
现在,为了确保取消订阅某些内容,您可以使用subscribe的第三个参数：
this.service.method().takeUntil(this.onDestroy$).subscribe(
onNext => ...,onError => ...,onComplete => console.log('stream has been completed')
);
如果你不想在subscribe方法中添加任何东西,你可以这样做：
this.service.method().takeUntil(this.onDestroy$)
.do({
complete => console.log('stream has been completed')
})
.subscribe();
如果你想进一步了解这个主题,你应该阅读Ben Lesh的这篇优秀文章：https://medium.com/@benlesh/rxjs-dont-unsubscribe-6753ed4fda87
