Ionic 2 - 从存储值获取令牌并在HTTP请求之前设置Header

Question

我在登录后使用该ionic/storage包来存储api_tokenfor用户,因此我可以使用唯一令牌与API进行交互.

我面临的问题是我需要获取值,通过storage.get该值返回一个promise并导致我想要设置的标题没有及时设置.

我需要返回一个RequestOptions实例,但无法弄清楚如何添加我从promise中检索到的头.添加与localStorage同步的头文件在测试时工作正常,因此问题必须是异步执行.

createAuthorizationHeader(headers: Headers) {
    // this does add the header in time
    localStorage.setItem('api_token', 'some token');
    headers.append('Authorization', 'Bearer ' + localStorage.getItem('api_token'));

    // this does not add the header in time
    return this.storage.get('api_token').then((value) => {
        headers.append('Authorization', 'Bearer ' + value);
    });
}

getHeaders(path): RequestOptions {
    let headers = new Headers({
        'Accept': 'application/json',
        'Content-Type': 'application/json'
    });

    if(!this.isGuestRoute(path)) {
        this.createAuthorizationHeader(headers);
    }

    return new RequestOptions({ headers: headers });
}

get(path: string) {
    return this._http.get(this.actionUrl + path, this.getHeaders(path))
        .map(res => res.json())
        .catch(this.handleError);
}

编辑:工作代码现在看起来像这样

getApiToken(): Observable<Headers> {
    return Observable.fromPromise(this.storage.get('api_token'));
}

getHeaders(): Headers {
    return new Headers({
        'Accept': 'application/json',
        'Content-Type': 'application/json'
    });
}

get(path: string) {
    let headers: Headers = this.getHeaders();

    if(!this.isGuestRoute(path)) {
        return this.getApiToken().flatMap(data => {
            headers.append('Authorization', 'Bearer' + data);

            return this._http.get(this.actionUrl + path, { headers : headers })
                .map(res =>  res.json())
                .catch(this.handleError);
        });
    }

    return this._http.get(this.actionUrl + path, { headers : headers })
        .map(res => res.json())
        .catch(this.handleError);
}

Answer 1

查看我的类似问题Angular2 - 在另一个Observable中使用Observable返回方法的值

如果将Promise转换为a Observable,则可以使用rxjs flatMap函数.

让我告诉你那时你会有点像什么

getApiToken(): Observable<Headers> {
    return Observable.fromPromise(this.storage.get('api_token'));
   //OR return Observalbe.of(this.storage.get('api_token'));
}

getHeaders(): Headers { 
     //create all headers here except the 'api_token'
     .....
}


get(path: string): Observable<any> {
    let headers: Headers = this.getHeaders();
    return this.getApiToken().flatMap(data => {

       headers.append('Authorization', 'Bearer'+data);

       return this.http.get(this.actionUrl + path, headers)
          .map(res =>  res.json()) 
          .catch(this.handleError);
    });
}

或者(刚刚了解到这一点,所以不确定它是否会起作用)

createAuthorizationHeader(headers: Headers) {
    // this does add the header in time
    localStorage.setItem('api_token', 'some token');
    headers.append('Authorization', 'Bearer ' + localStorage.getItem('api_token'));

    // this does not add the header in time
    let api_token = await this.storage.get('api_token');
    headers.append('Authorization', 'Bearer ' + api_token);
}