angular – http提供程序Observable.toPromise()在promise链中没有按预期工作

如果我使用Ng2 http提供程序Observable.toPromise()支持调用promise启用方法,它按预期工作,但当我将它作为promise链的一部分使用时,它会在then处理程序处理完并返回结果之前解析返回的promise.

使Observable.toPromise()在promise链中工作的任何已知问题或我可能测试的替代方法使其成为与promise链兼容的结果？在http请求,promise链中的最后一项,已完成其异步请求并返回结果之前,我被此解析承诺阻止.

例如

this.myservice.getSomethingInvolvingingMultiplePromiseCalls().then(result => {
    let valueFromSomethingInvolvingMultiplePromiseCalls = result;
},err => { 
    console.error('landed in app.component outer promise rejected handler,see output window for details')
})

public getSomethingInvolvingingMultiplePromiseCalls(): Promise<String> {
    return this.getSomethingInvolvingPromiseCall().then(resultPromise1 => {
        let resultPromise1propertyFoo = resultPromise1.propertyFoo;
            return this.getSomethingInvolvingNg2httpProviderToPromiseCall(resultPromise1propertyFoo);
        }
        .then(resultPromise2 => {
            let resultPromise2propertyBar = resultPromise2.propertyBar;
            return resultPromise2propertyBar;
        }   
    }

getSomethingInvolvingNg2httpProviderToPromiseCall(arg1: String): Promise<String> {
   let body = 'some body content Leveraging arg1';
   let headers = new Headers({ 'Authorization': 'Bearer ' + accessToken,'Content-Type': 'application/x-www-form-urlencoded' });
   let options = new requestOptions({ headers: headers });

   return this.http.post(resourceBaseAddress + '/someRestApi',body,options).toPromise().then(response => {
        let responseJson = response.json();
        return responseJson['someJsonProperty'];
      });
    }
}

提前感谢任何见解或建议.

public getSomethingInvolvingingMultiplePromiseCalls(): Promise<String> {
    let resolveFn,rejectFn;
    let promise = new Promise((resolve,reject) => { resolveFn = resolve; rejectFn = reject; });

    this.getSomethingInvolvingPromiseCall().then(resultPromise1 => {
        this.getSomethingInvolvingNg2httpProviderToPromiseCall(resultPromise1).then(resultPromise2 => resolveFn(resultPromise2));
    }

    return promise;  // return the promise for outside callers to wait on
}