如何同步Angular2 http get？ [英] How to synchronise Angular2 http get?

问题描述

我理解使用observable我可以在请求完成时执行一个方法，但是我怎么能等到http get完成并使用ng2 http返回响应？

I understand using observable I can execute a method when the request is completed, but how can i wait till a http get is completed and return the response using in ng2 http?

getAllUser(): Array<UserDTO> {
    this.value = new Array<UserDTO>();
    this.http.get("MY_URL")
                    .map(res => res.json())
                    .subscribe(
                        data => this.value = data,
                        err => console.log(err),
                        () => console.log("Completed")
    );

    return this.value;
} 

返回时，value将为null，因为get是异步的..

the "value" will is null when its returned because get is async..

推荐答案

您不应该尝试使http调用同步。永远不是一个好主意。

You should not try to make http calls behave synchronously. Never a good idea.

来到你的 getAllUser 实现它应该从函数返回一个observable，调用代码应该订阅而不是你在方法本身内创建订阅。

Coming to your getAllUser implementation it should return an observable from the function and the calling code should subscribe instead of you creating a subscription inside the method itself.

类似

getAllUser(): Observable<UserDTO> {
        return this.http.get("MY_URL")
                        .map(res => res.json());
} 

在你调用代码时，你应该订阅并做任何你想做的事。

In you calling code, you should subscribe and do whatever you want.

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