userSchema.pre('save', function(next) {
	const user = this;
	// only rehash the password if the user alters the password!!!!!
	if (user.isModified('password')) {

		bcrypt.genSalt(10, function(err, salt) {

			if (err) { return next(err); }

			bcrypt.hash(user.password, salt, null, function(err, hash) {

				if (err) { return next(err); }
				user.password = hash;
				next();

			});
		});
	} else {
		next();
	}
});