异步每个调用而不是同步节点

Question

我想循环浏览参与者的一些预测并计算一些点。要知道玩家得到多少分，我需要打电话给mongodb（使用猫鼬）。然后我想保存每个参与者的分数（稍后会这样做）

我正在使用这个异步模块：http://caolan.github.io/async/

var calculateTeamPredictionsPerRound = function (roundId) {
  var roundScores = [];
  predictions.find({}, {}).exec(function (err, predictions) {
    console.log("predictions length: " + predictions.length)
    if (err) return console.error(err);
    async.each(predictions,
      function (prediction) {
        var teamScores = [];
        console.log("team length: " + prediction.Team.length + "deelnemer: " + prediction.Participant.Name)
        async.forEach(prediction.Team, function (player,callback) {
          console.log("for player: " + player.PlayerName + "participant: " + prediction.Participant.Name);
          teamScore.findOne({ RoundId: roundId, 'Player.Id': player.Id }, { Player: { $elemMatch: { Id: player.Id } } }).exec(function (err, player) {
            console.log(player.Player[0].Name);
            var playerScore = new Object;
            playerScore.Name = player.Player[0].Name;
            playerScore.Team = player.Player[0].Team;
            playerScore.Won = setWinScore(player.Player[0]);
            playerScore.Draw = setDrawScore(player.Player[0]);
            playerScore.Played = setPlayedScore(player.Player[0]);
            playerScore.RedCard = setRedCardScore(player.Player[0]);
            playerScore.YellowCard = setYellowCardScore(player.Player[0]);
            playerScore.Assist = setAssistScore(player.Player[0]);
            playerScore.Goals = setGoalScore(player.Player[0]);
            playerScore.OwnGoal = setOwnGoalScore(player.Player[0]);
            playerScore.TotalScore = playerScore.Won + playerScore.Draw + playerScore.Played + playerScore.RedCard + playerScore.YellowCard + playerScore.Assist + playerScore.OwnGoal + playerScore.Goals;
            teamScores.push(playerScore)
          });
          callback();       
        });
      });
  });
};

当我运行此代码时，控制台向我显示以下内容：

team length: 11 participant: test   
for player: a participant: test  
for player: b participant: test  
for player: c participant: test  
for player: d participant: test  
for player: e participant: test  
for player: f participant: test  
for player: g participant: test  
for player: h participant: test  
for player: i participant: test  
for player: j participant: test  
for player: k participant: test  
team length: 11participant: test2  
for player: a participant: test2  
for player: b participant: test2  
for player: c participant: test2  
for player: d participant: test2  
for player: e participant: test2  
for player: f participant: test2  
for player: g participant: test2  
for player: h participant: test2  
for player: i participant: test2  
for player: j participant: test2  
for player: k participant: test  
a  
b  
c  
d  
e  
f  
g  
h  
i  
j  
k  
a  
b  
c  
d  
e  
f  
g  
h  
i  
j  
k  

但我想要：

team length: 11participant: test  
for player: a participant: test  
a  
for player: b participant: test  
b  

Answer 1

问题是在你的async.forEach方法中，你使用了一个.findOne()方法，它也是异步的。

执行顺序为：

1. console.log（"for player： " + player.玩家名称 + "参与者：" + prediction.Participant.Name）;
2. 查找一（）
3. 回调（）

你调用异步函数的回调（），而不等待 findOne（） 的回调，这是function (err, player) {...} 。

将 callback（） 移到 function (err, player) {...} 内部以等待 findOne（） 执行，然后再完成异步任务。

teamScore.findOne({ RoundId: roundId, 'Player.Id': player.Id }, { Player: { $elemMatch: { Id: player.Id } } }).exec(function (err, player) {
            console.log(player.Player[0].Name);
            var playerScore = new Object;
            playerScore.Name = player.Player[0].Name;
            playerScore.Team = player.Player[0].Team;
            playerScore.Won = setWinScore(player.Player[0]);
            playerScore.Draw = setDrawScore(player.Player[0]);
            playerScore.Played = setPlayedScore(player.Player[0]);
            playerScore.RedCard = setRedCardScore(player.Player[0]);
            playerScore.YellowCard = setYellowCardScore(player.Player[0]);
            playerScore.Assist = setAssistScore(player.Player[0]);
            playerScore.Goals = setGoalScore(player.Player[0]);
            playerScore.OwnGoal = setOwnGoalScore(player.Player[0]);
            playerScore.TotalScore = playerScore.Won + playerScore.Draw + playerScore.Played + playerScore.RedCard + playerScore.YellowCard + playerScore.Assist + playerScore.OwnGoal + playerScore.Goals;
            teamScores.push(playerScore)
            callback();  
          });         
        });

此外，您可以callback(playerScore) ，而不是teamScores.push(playerScore)，然后向 async.forEach 提供最终回调，当所有任务完成后，将使用所有 playerScore 的数组调用该回调。

如果async.forEach是这个模块，我不确定你为什么需要它，因为你的所有任务都是异步的。它不会自动使teamScore.findOne()同步，您仍然必须使用 var done = this.async(); 指定一个异步回调并在 findOne（） 完成后调用它，但您也可以使用常规的 async.each（） 代替。