pre function not called in mongoose - node.js

Question

I am trying to encrypt password on registration using mongoose and mongodb but pre function is not called at all.
var mongoose = require('mongoose');
var Schema = mongoose.Schema,
bcrypt = require('bcrypt'),
SALT_WORK_FACTOR = 10;
var patientSchema = new Schema({
username: {type: String, trim: true, index: { unique: true }},
password: {type: String, required: true}
});
//====================== Middleware:Start==========================//
patientSchema.pre('save', function(next) {
console.log('pre called'); //This is not printed at all
var user = this;
// only hash the password if it has been modified (or is new)
if (!user.isModified('password')) return next();
// generate a salt
bcrypt.genSalt(SALT_WORK_FACTOR, function(err, salt) {
if (err) return next(err);
// hash the password along with our new salt
bcrypt.hash(user.password, salt, function(err, hash) {
if (err) return next(err);
// override the cleartext password with the hashed one
user.password = hash;
next();
});
});
});
//======================Middleware:End===========================//
//======================API Routes:Start===========================//
router.route('/signup')
.post(function (req, res) {
console.log('post signup called', req.body);
var patients = new Patients({
username: req.body.username,
password: req.body.password
});
Patients.findOne({username: req.body.username}, function (err, user) {
if (err) {
console.log('user not found');
}
if (user) {
console.log("patient already exists");
res.json({message: 'patient already exists'});
} else {
//Saving the model instance to the DB
patients.save(function (err) {
if (err)
throw err;
console.log("user Saved Successfully");
res.json({message: 'user Saved Successfully'});
});
}
});
});
module.exports = router;
//======================API Routes:End===========================//
Inside the pre function, console.log('pre called'); is not printed at all. What am I missing here?

Answer 1

it might be solve your error.
const patients = new Patients({
username: req.body.username,
password: req.body.password
})
if(!patients) return res.json(patients)
patients.save((err,patients) => {
if(err) return res.json({status: 500, message: err})
return res.json({status: 200, user: patients})
})
Thank you.