Why this method of mongoose is not working if it's specified in the schema?

Question

I have this following error thrown when calling a custom method.

user.model.js

const userSchema = new Schema({
   (... HERE GOES THE SCHEMA ...)
}, {
    timestamps: true
});

/**
 * Login check password method
 */
userSchema.methods.checkPass = function (password, callback) {
    bcrypt.compare(password, this.password, function (err, same) {
        if (err) {
            callback(err);
        } else {
            callback(err, same);
        }
    });
}

auth.js

router.route('/').post((req, res) => {

    let findUser = User.findOne({
        username: req.body.username
    }, function (err, user) {
        if (err) {
            // err
        } else if (!user) {
            // err
        } else {

            findUser.checkPass(req.body.password, function (err, same) {
                // THIS IS NOT CALLED! 
                // Error thrown: TypeError: findUser.checkPass is not a function
            })

        }
    })

});

How it cannot be a method if checkPass is put as a method on the Schema?

Thank you for your time!

Answer 1

SOLVED!

I was using the User schema when calling the method instead of calling user from the callback of findOne .

Solved code:

User.findOne({
        username: req.body.username
    }, function (err, user) {
        if (err) {
            // Error!
        } else if (!user) {
            // Error!
        } else {

            user.checkPass(req.body.password, function (err, same) {
                if (err) {
                    // Error!
                } else if (!same) {
                    // Invalid !
                } else {
                    // SUCCESS !
                }
            })

        }
    })