Subscribe object to Angular Firebase

I'm doing an application on Angular 6, I created a class, how can I subscribe an array of objects of my class on a firebase realtime db? I'd like to modify these objects without any need to update array. Is it possible? How can I transform the db list into an array of objects with my class on the subscribe? Thank you

This is the class now, I will add functions

export class Bet {
  private name: string;
  private date: Date;
  private bet: number;
  private payout: number;
  private won: boolean;
  private type: string;
}

This is the function I tried to use to subscribe object list to db

this.afdb.list<Bet>('/Users/'+ uid + '/bets').valueChanges().subscribe( dbbets 
=> {
       this.bets = dbbets;
});

I'd like to add a new object of class Bet to this.bets and update automatically the db, is possibile with subscribe?