MongoDB object not updating

Question

I am working on a database system using MongoDB. I am trying to save the current date and time, then update it if the same barcode on ID cards is scanned twice, thrice, etc... However, the $set will not update the item. I have already looked at MongoDB documentation and other Stack Overflow posts, but nothing seems to work. Other Stack Overflow posts suggested adding

{ new: true }

and

( overwrite: true }

I tried these both separately and in tandem neither worked.

My Code:

Student.findOne({StudNum: studNum}, function(err, studNumItem) {
   if (err) {
    res.send("MongoDB Error: " + err);
    return false;
   }
   if (!studNumItem) {
    var myData = new Student({ StudNum: studNum, Attendance : 1, LastDateTimeAttended : {
        Year: year, Month: month, Day: day, Hours: hours, Min: min, Sec: sec
    }});
    myData.save()
      .then(item => {
        res.send("saved to database: " + studNum + ", with attendance " + Attendance + "");
      })
      .catch(err => {
        res.send("unable to save to database: " + studNum + ", for attendance " + Attendance + "");
      });
    }
    else{
      var conditions = {StudNum: studNum};
      var update = {$inc : { Attendance: 1 }, $set : {
        "Year": year, "Month": month, "Day": day, "Hours": hours, "Min": min, "Sec": sec
      }};
      Student.findOneAndUpdate(conditions, update, { new: true }, function (err)
      {
          if (err) // If error
          {
            res.send(err);
          }
          else {
            res.send("Checked in!")
          }
      });
 }

});

And my Schema:

var studentSchema = mongoose.Schema({
StudNum: String,
Attendance: Number,
LastDateTimeAttended: {
  Year: Number,
  Month: Number,
  Day: Number,
  Hours: Number,
  Min: Number,
  Sec: Number
}
});

Thanks in advance!

Edit: Just to clarify, saving the item works fine, but updating the item does not, also no errors are thrown while updating.

Answer 1

In your case, i'm not sure it is your find one and update that is the issue. I believe since what you are trying to update is a nested object, you need to prepend it with the top level property to get mongoose to save it. Since those properties don't exist at a top level, mongoose is just throwing it away.

var update = {$inc : { Attendance: 1 }, $set : {
    "LastDateTimeAttended.Year": year, "LastDateTimeAttended.Month": month, "LastDateTimeAttended.Day": day, "LastDateTimeAttended.Hours": hours, "LastDateTimeAttended.Min": min, "LastDateTimeAttended.Sec": sec
  }};

Answer 2

i suggest you try saving you date as a string. LastDateTimeAttended in your model should expect a string, and new Student constructor should create LastDateTimeAttended variable by calling

let date = new Date();
LastDateTimeAttended = date.toString();

your new schema should look like

var studentSchema = mongoose.Schema({
StudNum: {type: String, required: true},
Attendance: {type: Number, required: true},
LastDateTimeAttended: {type: String, required: true}
});

you should then be able to update your mongodb document Student.findOneandUpdate(conditions, update, callback). see working with mongoose Model.findOneandUpdate

Answer 3

对于那些不知道问题原因的人，也可能是方案中未声明变量，导致任何更改被暂停和忽略。