MongoDB - cannot remove multiple record from the same session - node.js

Question

I am trying to delete two record from different database (practice log, student) within the same session, the problem is the practice log record is found successfully and shown in console.log(deletePracticeLog), but it cannot be remove from the database. anyone know what have I done wrong? I am very confused.
const deleteStudentById = async (req, res, next) => {
const sid = req.params.sid;
let deleteStudent;
let deletePracticeLog;
try {
deleteStudent = await Students.findById(sid).populate("teacher");
} catch (err) {
const error = new HttpError("Delete failed, please try again.", 500);
return next(error);
}
try {
deletePracticeLog = await PracticeLog.find({ student: sid }).exec();
console.log(deletePracticeLog); // **<-this correctly show the record needed to be deleted, it's a object within an array**
} catch (err) {
const error = new HttpError("Cannot delete, please try again.", 500);
return next(error);
}
if (!deleteStudent) {
const error = new HttpError("Could not find student for this id.", 404);
return next(error);
}
try {
const sess = await mongoose.startSession();
sess.startTransaction();
await deleteStudent.remove({ session: sess }); //delete the student from student database
deleteStudent.teacher.students.pull(deleteStudent); //delete the student id from teacher database
await deleteStudent.teacher.save({ session: sess });
await deletePracticeLog.remove({ session: sess }); // **<-this line caused error, when this line is removed, other code run successfully and other record are deleted.**
await sess.commitTransaction();
} catch (err) {
const error = new HttpError("Cannot delete student with provided id.", 500);
return next(error);
}
res.status(200).json({ message: "Deleted student." });
};

Answer 1

when you are using await, you don't need to exec()
delete your exec() from
deletePracticeLog = await PracticeLog.find({ student: sid }).exec();
change to
deletePracticeLog = await PracticeLog.find({ student: sid })
beacuse you use exec(), use this code for remove data
await deletePracticeLog[0].remove({ session: sess })
if the result of PracticeLog.find({ student: sid }) is one Array and you want to delete all of them, you have to use deleteMany like this:
PracticeLog.deleteMany({ student: sid }).session(sess)
it's worked for me

Answer 2

here is the Mongoose schema:
const mongoose = require("mongoose");
const studentsSchema = new mongoose.Schema({
name: { type: String, require: true },
email: { type: String, require: true },
contact: { type: String, require: true },
teacher: { type: mongoose.Types.ObjectId, require: true, ref: "teachers" },
practiceLogs: [
{ type: mongoose.Types.ObjectId, require: true, ref: "practice_logs" },
],
});
module.exports = mongoose.model("students", studentsSchema);
const practiceLogSchema = new mongoose.Schema({
repertoire: { type: String, require: true },
student: { type: mongoose.Types.ObjectId, require: true, ref: "students" },
teacher: { type: mongoose.Types.ObjectId, require: true, ref: "teachers" },
});
module.exports = mongoose.model("practice_logs", practiceLogSchema);
here is the mongoose.connect():
const url =
"myURL";
mongoose
.connect(url, { useUnifiedTopology: true, useNewUrlParser: true })
.then(() => {
app.listen(5000);
console.log("connected.");
})
.catch((err) => {
console.log(err);
});