Angular 2 Observable 订阅不工作

Question

我正在尝试订阅组件初始化时的可观察对象，如下所示：

    this.ticketService.getTicketsAsync(filters).subscribe(
        tickets => this.ticketResponse = tickets,
        () => console.log('hi'))

为什么第一个 lambda 表达式有效，而第二个 lambda 表达式却不能？

编辑：

这是 getTicketAsync 返回的代码：

getTicketsAsync(ticketFilters : TicketSearch): Observable<TicketResponse> {

    let api_endpoint = AppSettings.API_ENDPOINT + 'WebReport/request_report'
    let headers = new Headers({ 'Content-Type': 'application/json' });
    let options = new RequestOptions({headers : headers, withCredentials : true});
    return this.http.post(api_endpoint, ticketFilters, options).map(this.extractData).catch(this.handleError);





}

Answer 1

第二个是catch when observable throw error.

subscription = source.subscribe(
  x => console.log('onNext: %s', x),
  e => console.log('onError: %s', e),
  () => console.log('onCompleted'));

https://github.com/Reactive-Extensions/RxJS/blob/master/doc/api/core/operators/subscribe.md

解法： 1.使用onNext钩子：

this.ticketService.getTicketsAsync(filters).subscribe(
    tickets => {
      this.ticketResponse = tickets;
      console.log('hi');
    },
    () => console.log('ERROR!'));

2。使用 onCompleted 挂钩：

this.ticketService.getTicketsAsync(filters).subscribe(
  tickets => this.ticketResponse = tickets,
  error => console.log('ERROR: ' +error),
  () => console.log('hi')
);

Answer 2

大箭头代表使您的代码像这样的函数

this.ticketService.getTicketsAsync(filters)
.subscribe(
  function(tickets){
    this.ticketResponse = tickets,
    function(){
      console.log("hi")
    }
  }
)

您正在传递两个参数（这是两个回调函数）。

Angular 2 Observable 订阅不工作

Angular 2 Observable subscribe not working

angular

angular2-observables