angular2将http请求的结果传递给mergemap http请求

Question

我正在尝试获取一种方法的结果，该方法返回一个可观察对象以传递给第二个请求

this.runfirstmethod(headers).mergeMap(response => this.http[verb](url, response).map(res => res.json()))

这就是我正在做的一切，我认为我做错了什么，因为我无法从 buildAzureHeaders 获取标头。

服务

    buildAzureHeaders(headers): Observable<Headers> {

    if (headers == null) {
        headers = new Headers();
    }

    if (JSON.parse(localStorage.getItem('azureToken')).token == null || this.azureAccessToken == null) {
        this.Adal4Service.acquireToken("https://graph.windows.net").map(token => {
            this.azureAccessToken = token;
            localStorage.setItem('azureToken', token);
            headers.append('Authorization', "Bearer " + token);
            return Observable.of(headers);
        });
    } else {
        headers.append('Authorization', "Bearer " + localStorage.setItem('azureToken', JSON.parse(localStorage.getItem('azureToken')).token));
        console.log("Headers: " + headers);
        return Observable.of(headers);
    }
}

invokeRequest(verb, url, headers?, body?): Observable<any> {
    return this.buildAzureHeaders(headers).switchMap(builtHeaders => this.http[verb](url, builtHeaders))
}

组件

this.ApiAuthService.invokeRequest("get","https://graph.windows.net/aseracare.com/users?api-version=1.6").subscribe(res => {
    console.log(res);
  });

Answer 1

class MyClass {

    firstMethod(headers: object): Observable<object> {
        return Observable.of({qwerty: 123456});
    }

    secondMethod(something: object): Observable<string> {
        return Observable.of('OK');
    }

    runner(): void {
        const obj = {a:1};
        this
            .firstMethod(obj)   // object -> Observable
            .switchMap(         // Observable -> object
                (returnedObject: object) => this.secondMethod(returnedObject)  // object -> Observable
            ).subscribe((x: string) => console.log(x)) // logs 'OK'
    }
}

SwitchMap 将第一个 observable “转换”为第二个 observable 可以接收的值。

如需更精确的文档，请查看 here 和 here