javascript - Any workaround for this method without convert snapshotChanges() into promise?

Question

I want to return cartIdFire but it returns undefined because snapshot method is return observable
so, there is any workaround for returning cartIdFire without convert snapshot method into promise ?

private async getServer() 
{
   this.db.list('/shopping-carts/').snapshotChanges()
   .subscribe(x => this.cartIdFire = x);
   return cartIdFire;
 }   

private async getOrCreateCartId() //to create a cartid or acceess the cartid
  
  {
    let cartId = localStorage.getItem('cartId'); //to create a cartid or acceess 
    if(cartId) 
    {
      return cartId;
    }
     this.id = await this.getServer();
     console.log(this.id);
     console.log(this.cartIdFire); //it gives undefined
    if(this.cartIdFire)
    {
       localStorage.setItem('cartId' ,result.key);
       return this.cartIdFire;
    } 
      let result =  await this.create(); 
      localStorage.setItem('cartId' ,result.key);
      return  result.key;
  }

so i can't return subscriber from getServer() method. Because i have to save
the cartFireId in the local storage.

Answer 1

In this scenario, await this.getServer() will not work, it will not wait to be solved, it only works in Promise, not in Observable, where it is solved within the subscribe

A simple solution would be, in the getServer() method to convert the Observable to Promise, using toPromise() and returning this value

private async getServer() 
{
   return this.db.list('/shopping-carts/').snapshotChanges().toPromise()
}

And get the cartIdFire in the getOrCreateCartId() method

this.cardIdFire = await this.getServer()