Firestore使用快照删除文档

Question

 players2:Observable<String[]>;

deletePlayerFromAvailable(id:string, firstName:string, lastName:string): Observable<String[]>{



    this.matchDoc = this.afs.doc<Match>(`matches/${id}`);
    this.players2 = this.matchDoc.collection<String>('availablePlayers', ref => ref.where('firstname', '==' , firstName)).valueChanges()



    return this.players2;

  }

我可以使用valueChanges（）方法检索数据，但我需要此动态查询的文档ID才能从＆lt; availablePlayers＆＃39;中删除文档。采集。我如何实现这一目标？当我开始使用SnapshotChanges（）方法时，错误是

Type 'Observable<DocumentChangeAction[]>' is not assignable to type 'Observable<String[]>'.

on this.players2

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编辑2 检索我需要的doc ID字符串的新方法，但是方法没有返回任何值 - 控制台打印未定义。

  getPlayerFromMatchDayAvailable(player:Player, id:String):string{

  this.playerscollection = this.afs.collection<Player>(`matchdays/${id}/availablePlayers`, ref => ref.where('email','==','john@test.com'))
  this.players2 = this.playerscollection.snapshotChanges()
  this.players2.subscribe( data => {
    if(data){
      console.log(data);
      data.map(test => {
        console.log(test.payload.doc.id);
        this.af = test.payload.doc.id;

      });

    }

  })

  console.log(this.af)
  return this.af;



  //  this.players2.forEach(player => {
  //    player.forEach(playerData => {
  //      let data = playerData.payload.doc.data();
  //      let ids = playerData.payload.doc.id;
  //      this.af = playerData.payload.doc.id;
  //      console.log(id,data)

  //    });
  //  });




  }