如何向AngularFire 2版本5中添加到节点的对象添加键

我以前可以在AngularFire2 v.4.x中向对象本身添加键,如下所示:

addMatchToDb(match: any){
    let ref = this.db.object('matches/');
    let matchId = this.matches.push(match).key;
    let updates = {};
    updates['/matches/' + matchId + '/id'] = matchId;
    updates['/matches/' + matchId + '/matchCreated'] = firebase.database.ServerValue.TIMESTAMP;
    firebase.database().ref().update(updates);
  }

因为我出错了

错误TS2339:类型“observable”上不存在属性“push”<“any”>。

,我考虑重构到:

addMatchToDb(match: any){
    let ref = this.db.object('matches/');
    let matchId = ref.update(match);
  }

但是现在我无法将密钥添加为ID或时间戳。对版本5的新更改有什么建议吗?

更新:有关此的一些详细信息。匹配:

export class DatabaseService {
  matches:Observable<any>;
  weightClasses:Observable<any>;
  giRanks:Observable<any>;
  noGiRanks:Observable<any>;
  ageClasses:Observable<any>;
  users:Observable<any>;
  currentUser:Observable<any>;
  moves:Observable<any>;
  retrievedMatch:Observable<any>;

  constructor(private db: AngularFireDatabase, private textTransformationService: TextTransformationService) {
    this.matches = db.list<Match>('/matches').valueChanges();
    this.weightClasses = db.list<string>('/weightClasses').valueChanges();
    this.giRanks = db.list<string>('/giRanks').valueChanges();
    this.noGiRanks = db.list<string>('/noGiRanks').valueChanges();
    this.ageClasses = db.list<string>('/ageClasses').valueChanges();
    this.users = db.list<User>('/users').valueChanges();
    this.moves = db.list<string>('/moves').valueChanges(); //TODO maybe JSON?
  }