angular 服务功能完成时通知组件 [英] Notify component when service function is complete in angular

问题描述

我编写了一个对后端执行 http 查询的服务:

I writing a service which do a http query to the backend:

getPlacesForUser(){
 this.http.get("http://localhost:8080/processPlaces")
  .map(res => res.text())
  .subscribe(
    data => this.result = data,
    err => this.logError(err),
    () => console.log('Places Request completed')
  )
}

现在我想更新组件端，如果请求完成:

Now I want to update the components-side, if the request is completed:

processPlaces(){
 this._backendService.getPlacesForUser();
}

如何在组件和服务之间进行通信?

How can I communicate between the component and service?

此外，我还在寻找最佳实践.

Furthermore I searching for the best practice.

推荐答案

实际上，您可以直接从 getPlacesForUser 方法返回 observble 并在其上附加 subscribe 方法.

In fact, you can return the observble directly from the getPlacesForUser method and attach a subscribe method on it.

• 服务

getPlacesForUser(){
  return this.http.get("http://localhost:8080/processPlaces")
    .map(res => res.text());
}

组件

processPlaces(){
 this._backendService.getPlacesForUser()
  .subscribe(
    data => this.result = data,
    err => this.logError(err),
    () => console.log('Places Request completed')
  );
}

result 属性对应于您可以在组件中使用的组件的属性.

The result attribute corresponds to an attribute of the component you can use in the component.

您可以注意到 async 管道可用于直接利用表达式中的 observable(例如在 ngFor 中).

You can notice that a async pipe is available to directly leverage observable in expressions (for example within an ngFor one).

我认为这个答案可以帮助您:如何在 angular 2 beta 的服务中有效地使用 Http 组件?.

I think that this answer could help you: How to Consume Http Component efficiently in a service in angular 2 beta?.

希望对你有帮助蒂埃里

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