node.js - Model.find({_id :req. body.id}) 找到该对象，但 Model.updateOne({_id :req. body.id},{//update}) 未找到该对象

Question

app.post("/admin/editAssignedTask/:id", (req, res) => {
  Task.findById(req.params.id, (err, task) => {
    task.title = req.body.title;
    task.priority = req.body.priority;
    task.date = new Date(req.body.date);
    task.description = req.body.description;
    if (req.body.assignTo) {
      console.log(req.body.assignTo);
      if (typeof req.body.assignTo == "string") {
        task.assignedTo = [...task.assignedTo, req.body.assignTo];
        Staff.find({ _id: req.body.assignTo }, (err, staff) => {
          console.log(staff);
        });
        Staff.updateOne(
          { _id: req.body.assignTo },
          { $set: { $push: { todo: req.params.id } } },
          (err, up) => {
            console.log(up);
          }
        );

在上面的代码中，staff.find() 返回

 [ { todo: [ 5cc44b02abde080691893e41, 5cc46186db0195071f117808 ],
 completed: [],
 _id: 5cc34724ab9d2d231642f925,
 name: 'gokul',
 mailId: 'gokul',
 __v: 12 } ]

但是 Staff.updateOne() 返回{ 确定:0，n:0，n修改:0 }这里 n 是 0，这意味着没有对象匹配。!为什么会出现这种情况？

下面是员工架构

var userSchema = new mongoose.Schema({
  name: String,
  mailId: String,
  todo: [
    {
      type: mongoose.Schema.Types.ObjectId,
      ref: "Task"
    }
  ],
  completed: [
    {
      type: mongoose.Schema.Types.ObjectId,
      ref: "Task"
    }
  ]
});

Answer 1

改变

Staff.updateOne(
  { _id: req.body.assignTo },
  { $set: { $push: { todo: req.params.id } } },
  (err, up) => {
    console.log(up);
  }
);

至

Staff.updateMany(
  { _id: { $in: req.body.assignTo } },
  { $push: { todo: mongoose.Types.ObjectId(req.params.id) } },
  (err, up) => {
    console.log(up);
  }
);

1) 不要使用 $set 来插入或拉出数组元素。

2) 由于在模式中，属性“todo”是一个 objectID 数组而不是字符串，因此我们需要使用 mongoose.Types.ObjectId() 显式地将字符串转换为 objectID