javascript - 返回正确的 Observable<Response> 而不是 Promise 本身

Question

我正在制作一个 HTTP 请求拦截器并且我正在覆盖 Http模块 get方法，以便我可以自动将 JWT token 添加到 header 。

我已经用下面的代码试过了，但是从方法返回时我得到了以下错误:

Type Promise<Observable<Response>> is not assignable to type Observable<Response>.

即使我尝试在 then() 内归还它它给了我同样的错误。

如何获得正确的 Observable<Response>并归还？

// ...

@Injectable()
export class AdalHttp extends Http {
  constructor(backend: ConnectionBackend, defaultOptions: RequestOptions) {
    super(backend, defaultOptions);
  }

  get(url: string, options?: RequestOptionsArgs): Observable<Response> {
    return this.getWithAdal(url, options); // <-- ERROR HERE
  }

  private getWithAdal(url: string, options?: RequestOptionsArgs): Promise<Observable<Response>> {
    return new Promise((resolve, reject) => {
      this.authenticate((authResponse) => {
        if (!options) {
          options = { headers: new Headers() };
        }

        options.headers.set('Authorization', 'Bearer ' + authResponse.accessToken);

        resolve(super.get(url, options));
      }, err => reject(err));
    });
  }

  // ...
}

Answer 1

get 方法应该返回 Observable。它调用 getWithAdal 方法并立即返回 getWithAdal 返回的对象。所以 getWithAdal 也应该返回 Observable。

使用 Observable.fromPromise 将 promise 转换为 Observable，更改 getWithAdal 方法的签名以返回 Observable

    get(url: string, options?: RequestOptionsArgs): Observable<Response> {
      return this.getWithAdal(url, options); // <-- ERROR HERE
    }

    private getWithAdal(url: string, options?: RequestOptionsArgs): Observable<Response> {
      return Observable.fromPromise(new Promise((resolve, reject) => {
        // just make it simpler for the example.... keep your code here as is
        let options = {headers: new Headers()};
        options.headers.set('Authorization', 'Bearer ');
        resolve(super.get(url, options));
      }));
    }