Mongoose unable to get _id from Schema - node.js

Question

I 've a UserSchema that looks like:
export var UserSchema: Schema = new mongoose.Schema({
createdAt: Date,
email: {
type: String,
required: true,
trim: true,
unique: false,
},
firstName: {
type: String,
required: false,
trim: true
},
lastName: {
type: String,
required: false,
trim: true
},
password: {
type: String,
trim: true,
minlength: 6
},
tokens: [{
access: {
type: String,
required: true
},
token: {
type: String,
required: true
}
}]
});
And I 've a instance method like:
UserSchema.methods.printThis = () => {
var user = this;
console.log("========>>> PRINTING USER NOW");
console.log(user);
};
The method printThis is being called from
router.post('/signup', (req, res) => {
var body = _.pick(req.body, ['email', 'password']);
var user = new User(body);
console.log("created user as: ", user);
user.printThis();
});
Below is the output:
created user as: { email: 'prsabodh.r#gmail.com',
password: '123456',
_id: 59be50683606a91647b7a738,
tokens: [] }
========>>> PRINTING USER NOW
{}
You can see that the user is getting created properly. However, when I call printThis method on User - I'm not able to print the same user back and an empty {} is printed. How to fix this?

Answer 1

You shouldn't use arrow functions (=>) if the calling function is explicitly setting a context (which is what Mongoose does):
UserSchema.methods.printThis = function() {
var user = this;
console.log("========>>> PRINTING USER NOW");
console.log(user);
};
More info on arrow functions and their handling of this here: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/this#Arrow_functions

Answer 2

To get the _id value from the instance method can use _conditions that should work
UserSchema.methods.printThis = function(password) {
var user = this;
console.log(user._conditions['_id']);
};