Angular2 Http设置头部Access-Control-Allow-Origin和http CORS

Question

我正在使用Angular2 RC5(核心,http等)并尝试连接到启用CORS的Node.js服务器.我的应用程序是从Angular-CLI生成的新版本(版本:"1.0.0-beta.11-webpack.2").

// src/app/app.component.ts
...
ngOnInit () {
   const headers: Headers = new Headers();
   headers.append('Accept', 'application/json');
   headers.append('Content-Type', 'application/json');
   headers.append('Access-Control-Allow-Origin', '*');

   const options = new RequestOptions({
     headers: headers
   });

   this.http.get('http://localhost:9000/api/v1/users', options)
    .map((res: Response) => res.json())
    .subscribe(users => console.log(users));
}

...

当应用程序启动时,OnInit挂钩被调用,我在控制台中出错.这是我收到的错误消息.

EXCEPTION: TypeError: Cannot read property 'toString' of null
browser_adapter.js:84EXCEPTION: TypeError: Cannot read property 'toString' of nullBrowserDomAdapter.logError @ browser_adapter.js:84BrowserDomAdapter.logGroup @ browser_adapter.js:94ExceptionHandler.call @ exception_handler.js:65(anonymous function) @ application_ref.js:267ZoneDelegate.invoke @ zone.js:323onInvoke @ ng_zone_impl.js:53ZoneDelegate.invoke @ zone.js:322Zone.run @      zone.js:216(anonymous function) @ zone.js:571ZoneDelegate.invokeTask @ zone.js:356onInvokeTask @ ng_zone_impl.js:44ZoneDelegate.invokeTask @ zone.js:355Zone.runTask @ zone.js:256drainMicroTaskQueue @ zone.js:474
zone.js:461 Unhandled Promise rejection: Cannot read property 'toString' of null ; Zone: <root> ; Task: Promise.then ; Value: TypeError: Cannot read property 'toString' of null(…)consoleError @ zone.js:461_loop_1 @ zone.js:490drainMicroTaskQueue @ zone.js:494
zone.js:463 Error: Uncaught (in promise): TypeError: Cannot read property 'toString' of null(…)

如果我的掉落options和header完全,我从服务器CORS错误,但响应状态200.(我想如果我可以传递正确的标题,它应该可以工作.)

 this.http.get('http://localhost:9000/api/v1/users')
  .map((res: Response) => res.json())
  .subscribe(users => console.log(users)); 

这是控制台的错误

XMLHttpRequest cannot load http://localhost:4000/api/v1/users. No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://localhost:4200' is therefore not allowed access.
browser_adapter.js:93EXCEPTION: Response with status: 0  for URL: null
browser_adapter.js:84EXCEPTION: Response with status: 0  for URL: nullBrowserDomAdapter.logError @         browser_adapter.js:84BrowserDomAdapter.logGroup @    browser_adapter.js:94ExceptionHandler.call @ exception_handler.js:65next @ application_ref.js:348schedulerFn @ async.js:89SafeSubscriber.__tryOrUnsub @ Subscriber.js:225SafeSubscriber.next @ Subscriber.js:174Subscriber._next @ Subscriber.js:124Subscriber.next @ Subscriber.js:88Subject._finalNext @     Subject.js:128Subject._next @ Subject.js:120Subject.next @ Subject.js:77EventEmitter.emit @ async.js:77onHandleError @ ng_zone_impl.js:74ZoneDelegate.handleError @ zone.js:327Zone.runTask @ zone.js:259ZoneTask.invoke @ zone.js:423
Subscriber.js:229Uncaught Response with status: 0  for URL: null

有人可以帮帮忙吗？谢谢.

Answer 1

我是一个新手，所以请耐心等待，但就我而言，Access-Control-Allow-Origin 标头应该由后端 Node.js 服务器返回。出于安全考虑，服务器端的 CORS 默认处于禁用状态。使用以下问题来帮助您实施：如何允许 CORS？