映射和异步问题，值似乎不同，我该如何处理这个异步问题

Question

只是试图总结数据库中的值，然后对参数取平均值，但事情不会按预期工作，因为项目 1 和 2 是 100 和 33，对于两个用户来说，它应该是 66.5，但是只有其中一个获得所需的输出，请帮帮我，新手 :(

似乎有时有效，有时无效，但你知道演习，要么全部工作;-;

const sumItUp = async (project, sum) => {
  // console.log(project);
  await Project.findById(project, (err, result) => {
    // console.log(result.completion_percentage);
    sum += result.completion_percentage;
    console.log(result.title + " " + sum);
  });
  return sum;
};
const updateUserCompletion = async (user) => {
  // console.log(user);
  let sum = 0;
  for (var i = 0; i < user.projects.length; i++) {
    sum = await sumItUp(user.projects[i], sum);
    // console.log(user.name + " " + user.project[i].title + " " + sum);
  }
  // console.log(sum);
  user.completion_percentage_of_all_projects = sum / user.projects.length;
  user.save();
};
exports.updateTasks = async (request, res) => {
  let id = request.body.id;
  let project = request.projectObject;
  // console.log(id);
  let planned = 0,
    wip = 0,
    review = 0,
    completed = 0;
  project.tasks.map(async (task) => {
    if (task._id.toString() === id.toString()) {
      task.taskName = request.body.taskName;
      task.taskDescription = request.body.taskDescription;
      task.pessimisticTime = request.body.pessimisticTime;
      task.optimisiticTime = request.body.optimisiticTime;
      task.mostLikelyTime = request.body.mostLikelyTime;
      task.status = request.body.status;
    }
    if (task.status === "PLANNED") planned++;
    else if (task.status === "WIP") wip++;
    else if (task.status === "Review") review++;
    else if (task.status === "COMPLETED") completed++;
    // console.log(task._id.toString(), id.toString());
  });
  let total_task = planned + wip + review + completed;
  let comp_percentage =
    (planned * 0 + wip * 0.33 + review * 0.66 + completed) / total_task;
  // console.log(comp_percentage*100);
  // console.log(request.body);
  project.completion_percentage = comp_percentage * 100;
  console.log("completion percentage:", project.completion_percentage);
  const users = [];
  project.save((err) => {
    if (err) return res.status(400).json({ err: "Task not found" });
  });
  await project.team.forEach((user) => {
    User.findById(user, (err, res) => {
      if (err) {
        res.status(400).json({ err: err });
      } else {
        updateUserCompletion(res);
      }
    });
  });
  // console.log(users);
  // console.log(request.body);
  return res.status(200).json({ project });
};

这是我的代码^

这些是输出： supposed to be the same :(

我的 2 个用户有 2 个项目： user 1 user 2

与他们相关的2个项目： project 1 project 2

Answer 1

我不能保证这是唯一的问题，但有一个问题是：要获得findById 的承诺，您必须使用.exec。使用 Promise 时，不要给它传递回调；相反，使用承诺的履行价值。所以：

const sumItUp = async (project, sum) => {
    // console.log(project);
    const {completion_percentage} = await Project.findById(project).exec();
    sum += completion_percentage;
    console.log(`completion_percentage is ${completion_percentage}, updated sum is ${sum}`);
    return sum;
};