角度2中的shareService-两次订阅下一个函数 [英] shareService in angular 2 - twice subscribe the next function

问题描述

我在角度2中有一个ShareService，在另一个组件中，我订阅了它，这是我的代码:

I have a ShareService in angular 2,and in another component i subscribe that,and this is my code :

*******ShareService ***********************************
   private ShopItem$ = new Subject<any>();
ShopItem$_ = this.ShopItem$.asObservable();
public addToCart(item : any){

    this.ShopItem$.next(item);

}

*************in another component**********************

_shareService.ShopItem$_.subscribe((item) => {

        alert("hiii"); <====>this functions execute twice
        this.ADD_TO_CART(item);<====>this functions execute twice

 });

我的问题是ADD_TO_CART()函数执行两次！为什么?我不希望我的购物车函数执行两次，如何解决此问题?ShareService没问题，我可以使用一个函数对其进行测试，然后执行.

my problem is ADD_TO_CART() function execute twice!why?i dont want my cart function execute twice,how to fix this problem?? the ShareService dont have any problem i test it with an function and once execute.

推荐答案

如注释中所述，这可能是由于多个订阅所致.要验证不是这样，您可以将您的订阅放在下面，即下面的行:

As discussed in the comments, this is probably due to multiple subscriptions. To verify it is not this, you can put just above your subscriptions, the following line:

console.log('pre subscribe, number of observers is: ', _shareService.ShopItem$_.source.observers.length);

注意，该功能适用​​于rxjs 4，在版本5中，您可能需要使用其他语法.

Note this works on rxjs 4, in version 5 you might need a different syntax.

应该给您0，如果您获得另一个值，则您已经有一个有效的订阅.

It should give you 0, if you get another value, you have an already active subscription.

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