typescript - 为什么这个订阅会变成 SafeSubscriber

我需要弄清楚为什么我的 this 对象在我的 TS 和 ionic 应用中会从 view controller 变成 SafeSubscriber。

我的数据服务：

getStationData(name:string){

        let myURL = "http://some/url/request.php?name="+ name;

        return this.http.get(myURL)
                .map(
                    res => {return this.parseData(res._body);},
                    err => console.log(err));
};

我的视图控制器：

//here, this is still the correct object : view controller
this._dataService.getStationData(name).subscribe((data) =>{
    //here, this now becomes of type safe subscriber?
    console.log(this);
    //when I hover in chrome over this, it shows all view controller parameters.
    //but when I call a method, it's not defined?
});

http.get 请求有问题吗？