Question

getEnrolledPlayers应该从数据库中获取“玩家”对象的数组，然后将其传递给matchMaking函数。但是，它不能正确传递。

我尝试添加可观察的事物，在订阅中玩耍

initializeEvent(eventId: string) {
  const enrolledPlayers: PlayerStat[] = [];
  this.getEnrolledPlayers(eventId)
    .subscribe((playerIds: string[]) => {
      for (const playerId of playerIds) {
        this.dataService.fetchSinglePlayer(playerId)
          .subscribe((playerStat: PlayerStat) => enrolledPlayers.push(playerStat));
      }
      this.matchMaking(enrolledPlayers);
    });
}

当我调用这些系列的异步函数时，enrolledPlayers []的计算正确（包含7个元素的数组），但是没有正确地调用matchMaking（）函数。我认为这是因为异步运行时。

Answer 1

是的。绝对是由于内部const query = `SELECT * FROM document_metadata m LEFT OUTER JOIN document_attributes a ON a.document_id = m.id;` db.query(query)解析值的时间差而引起的问题。

我建议使用forkJoin并等待所有值解析后再调用subscription。

尝试一下：

matchMaking

或带有一个initializeEvent(eventId: string) { const enrolledPlayers: PlayerStat[] = []; this.getEnrolledPlayers(eventId) .subscribe((playerIds: string[]) => { const playerInfos$ = playerIds.map(playerId => this.dataService.fetchSinglePlayer(playerId)); forkJoin(...playerInfos$) .subscribe(enrolledPlayers: PlayerStat[] => this.matchMaking(enrolledPlayers)); }); }

subscribe

Answer 2

this.matchingMaking(enrolledPlayers)由于异步而在enrolledPlayers准备就绪之前执行。

您需要将this.matchingMaking(enrolledPlayers)放入内部subscribe()中，然后进行for循环。

this.getEnrolledPlayers(eventId)
  .subscribe((playerIds: string[]) => {
  for (const playerId of playerIds) {
    this.dataService.fetchSinglePlayer(playerId).subscribe((playerStat: PlayerStat) => {
      enrolledPlayers.push(playerStat);
    });
  }
  this.matchMaking(enrolledPlayers);
});

Angular中连续异步函数的问题

2 个答案: