export declare type FirebaSEOperation = string | firebase.database.Reference | firebase.database.DataSnapshot | AFUnwrappedDataSnapshot;
export declare class FirebaseListObservable<T> extends Observable<T> {
  _ref: firebase.database.Reference | firebase.database.Query;
  constructor(_ref: firebase.database.Reference | firebase.database.Query,subscribe?: <R>(subscriber: Subscriber<R>) => Subscription | Function | void);
  lift<T,R>(operator: Operator<T,R>): Observable<R>;
  push(val: any): firebase.database.ThenableReference;
  update(item: FirebaSEOperation,value: Object): firebase.Promise<void>;
  remove(item?: FirebaSEOperation): firebase.Promise<void>;
  _checkOperationCases(item: FirebaSEOperation,cases: FirebaSEOperationCases): firebase.Promise<void>;
}

我有一个显示,保存,删除和更新房屋的服务,如下所示：

@Injectable()
export class HousesService {
  private _houses$:FirebaseListObservable<IHouse[]>;
  constructor(private af:AngularFire) {
    this._houses$= this.af.database.list('/houses');
  }
  save(house:IHouse) {
    if (house.hasOwnProperty('$key')) {
      this._houses.update('/houses/'+house.$key).set(house);
    } else {
      this._houses$.push(house);
    }
  }
  remove(id:any) {
    this._houses$.remove(id);
  }
}

houses $是FirebaseListObservable,house是列表中的项目. House是一个如下所示的对象：

{
  name: "Mrs. Friendly",notes: "Watch out for fence!",street: "2530 Adams Ave.",$key: "-KKQWsf26apDiXZNExZd"
 }

当我尝试保存/更新现有项目时,出现以下错误：

Uncaught Error: Firebase.update Failed: First argument contains an
invalid key ($key) in path /$key. Keys must be non-empty strings and
can’t contain “.”,“#”,“$”,“/”,“[“,or “]”

我已经尝试将原始对象放在第一个参数中,将完整的URL放在那里,几乎每个组合都可以想到.根据Observable的定义,_ref也应该在那里工作.我也尝试从要存储的数据中提取密钥,似乎没有任何工作.似乎唯一有效的方法是完全删除更新行并使用以下内容：

this.af.database.object('/houses/'+house.$key).set(house);

我很好奇我应该放在第一个参数中,以便更新方法可以工作.

我正在使用Angular 2 rc-1,firebase 3.0.5和angularfire 2.0.0-beta.1