javascript - 我可以在 Angular2 中可观察到的 RXJS 中捕获 "subscribe()"之前的某些错误吗？

Question

基类是否有可能在允许子类订阅 Angular2 中的可观察对象之前捕获某些错误。

例如

export class SomeBaseClass {
    constructor(private _http: Http, private _location: Location) {}

    protected _fetchData(url): Observable<any> {
        const headers = new Headers();
        headers.append('Authorization', 'Token foo');
        return this._http.get(url, {headers})
            .map(response => response.json())
            .catch(response => this._handle401(error));
    }

    private _handle401(response: Response) {
        if(response.status === 401) {
            this._location.go('/login');
        }

        // What should this return?
    }
}

export class SomeClass extends SomeBaseClass {
    constructor( _http: Http,  _location: Location) {
        super(_http, _location);
    }

    doTheThing() {
        this._fetchData('/someUrl')
            .subscribe(
                response => this._handleResponse(response),
                error => this._handleErrorThatIsNot401(error));
    }

    private _handleResponse(response) {
        // ...
    }

    private _handleErrorThatIsNot401(error) {
        // ...
    }
}

catch 是我要找的东西吗？我应该使用 map (或其他东西)吗？还是我完全以错误的方式解决了这个问题？

更新

这两个答案(到目前为止)都让我走上了正确的轨道，最终 - 我是这样解决的:

protected _get(url: string, data?: any): Observable<any> {
    return super._get(url, data, this._authorizationHeader)
        .map(response => response.json())
        .catch(response => this._handle401(response));
}

private _handle401(response: Response): Observable<any> {
    try {
        if(response.status === 401) {
            this._router.navigateByUrl('/login');      
            return Observable.throw(response.status);  
        }
    } catch(err) {
        console.warn('AuthenticatedHttpService._handle401');
        console.error(err);
    }

    return Observable.of(response);
}

Answer 1

单独使用 catch 没有多大帮助，因为您订阅了客户端代码并且您必须从 catch 返回 Observable。

我会按如下方式实现它:

Rx.Observable.of(42)
.do(v=>{throw new Error('test')})
.catch(Rx.Observable.of(undefined))
.filter(v=>{return v !== undefined})
.subscribe(
(e)=>{console.log('next', e)}, 
(e)=>{console.log('error', e)}, 
()=>{console.log('complete')}
);