如何从内部具有Observable订阅的函数返回值? [英] How to return value from function which has Observable subscription inside?

问题描述

我不知道如何从Observable中提取值以由存在Observable的函数返回.我只需要从中返回一个值，就别无所求.

I dont know how to extract value from Observable to be returned by function in which Observable is present. I need just a value from it to be returned, nothing else.

当前版本有效

function getValueFromObservable() {
    this.store.subscribe(
        (data:any) => {
            console.log(data)
        }
    )
}
getValueFromObservable()

我需要它工作，函数才能返回值，然后:

I need this to work, function to return value, and then:

function getValueFromObservable() {
    this.store.subscribe(
        (data:any) => {
            return data
        }
    )
}
console.log(getValueFromObservable())

我在做什么错了?

推荐答案

我意识到这个问题已经有一段时间了，您现在肯定已经找到了正确的解决方案，但是对于任何寻求此解决方案的人，我建议您使用保证保持异步模式.

I realize that this Question was quite a while ago and you surely have a proper solution by now, but for anyone looking for this I would suggest solving it with a Promise to keep the async pattern.

更详细的版本将创建一个新的Promise:

A more verbose version would be creating a new Promise:

function getValueFromObservable() {
    return new Promise(resolve=>{
        this.store
         .take(1) //useful if you need the data once and don't want to manually cancel the subscription again
         .subscribe(
            (data:any) => {
                console.log(data);
                resolve(data);
         })
    })
}

在接收端，您将等待"等待诺言解决，如下所示:

On the receiving end you will then have "wait" for the promise to resolve with something like this:

getValueFromObservable()
   .then((data:any)=>{
   //... continue with anything depending on "data" after the Promise has resolved
})

一种更苗条的解决方案是使用RxJS的.toPromise()代替:

A slimmer solution would be using RxJS' .toPromise() instead:

function getValueFromObservable() {
    return this.store
       .take(1)
       .toPromise()   
}

接收方当然与上面相同.

The receiving side stays the same as above of course.

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