Model.find（{_ id：req.body.id}）找到对象，但是Model.updateOne（{_ id：req.body.id}，{// update}）找不到对象

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);
          }
        );

上面的代码staff.find（）返回

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

但是staff.updateOne（）返回 {ok：0，n：0，nModified：0} 这里n为0，这意味着没有对象匹配。 为什么会这样？

下面是Staff模式

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

更改

app.get("/api/shorturl/:shorturl",function(req,res){
    let url=req.params.shorturl;
    console.log(req.params);
    console.log(req.url);
    if(url===""){
        res.send("no urls ");
    }
     try{
         url=parseInt(url);
         if (url>0 && url<=urls.length){
             res.redirect(urls[url],301);
         }
         else{
             res.send("we don't have this url");
             console.log(url);
         }
}
    catch(err){
        res.send("error occured");
}
});

到

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

1）不要使用$ set来推或拉数组元素。

2）由于在架构中，属性“ todo”是对象ID的数组而不是字符串，因此我们需要使用mongoose.Types.ObjectId（）明确将字符串转换为对象ID。