undefined field on mongoose Schema

Question

I'm getting an undefined field trying yo compare an user password

this is the function

logUser = (req,res) => {
       User.findOne({ username:req.body.username}, (err,user) => {
            if(!user){
                req.flash('error','El nombre de usuario no existe');
                res.redirect('/login');
            }else if(!user.comparePassword(req.body.password)){
                req.flash('error','La contraseña no es correcta');
                res.redirect('/login');
            }else{
                res.redirect('/');
            }
       });
    }

when the execution goes to the else if and uses comparePassword function the schema field is undefined

the schema file

const mongoose = require('mongoose');
const Schema = mongoose.Schema;
const bcrypt = require('bcrypt');

const userSchema = Schema({
    username:String,
    email:String,
    password:String,
    registrationDate: {type:Date, defaul: Date.now()}
});

userSchema.methods.encryptPassword = (password) =>{
    return bcrypt.hashSync(password, bcrypt.genSaltSync(10));
}

userSchema.methods.comparePassword = (password) =>{
    console.log('password: ',this.password);
    return bcrypt.compareSync(password, this.password);//here this.password is undefined
}

module.exports = mongoose.model('User',userSchema)

Debugging I saw that user object is not the schem class, what is worng with tuis class?

score 0 · Accepted Answer · answered Oct 11 '20 at 14:40

In short, it will work if you replace

userSchema.methods.comparePassword = (password) =>{
    console.log('password: ',this.password);
    return bcrypt.compareSync(password, this.password);//here this.password is undefined
}

with

userSchema.methods.comparePassword = function(password) {
    console.log('password: ',this.password);
    return bcrypt.compareSync(password, this.password);//here this.password is undefined
}

You are facing the problem because of lexical scoping of arrow function. Arrow function inherits its this scope from parent.

undefined field on mongoose Schema

1 Answers1