add new properties to object with variable name in mongoose

Question

I need to store responses to questions in Mongo. I am using Mongoose. My query looks like this right now:

router.post('/answers', expressJwt({secret: config.secret}), function (req, res, next) {
    var user = req.user
    var question = req.body.question
    var answer = req.body.answers
    var id = question._id

    db.User.update({email: user.email}, {$set: {answers[question._id]: answer}}, function (err, doc) {
        if (err) {
            console.error('problem updating answers object', err)
            return res.json(err)
        }
        console.log(doc)
        return res.json('successfully updated answers')
    })
})

I get an error 'unexpected token [' How can I add properties to my answers object?

I had to make a db call to get the answers object, then modify it, then update it back to the db. Here is the code I used. Note: use lean and exec with mongoose to get raw object otherwise you will run into problems modifying mongoose objects.

router.post('/answers', expressJwt({secret: config.secret}), function (req, res, next) {
    var user = req.user
    var question = req.body.question
    var answer = req.body.answers
    var id = question._id

    db.User.findOne({email: user.email}).lean().exec(function (err, user) {
        user.answers[question._id] = answer
        db.User.update({email: user.email}, {$set: {answers: user.answers}}, function (err, doc) {
            if (err) {
            console.error('problem updating answers object', err)
            return res.json(err)
        }
            console.log(doc)
            return res.json('successfully updated answers')
        })
    })
})

@mscdex Well, it depends on the context, but nothing in this case. I am trying to add a new property to the answers object which is the id of the question being answered : answer array. If you retrieved the user from the db and accessed this answers object, it would depend on whether or not they answered that specific question. — user137717
– user137717, Commented Sep 5, 2015 at 4:27
just looked up console.dir() the properties would be id : answers, id : answers for all questions. — user137717
– user137717, Commented Sep 5, 2015 at 4:34

Prabjot Singh · Accepted Answer · 2015-09-05 04:41:51Z

1

First,you have to set id in your answer object before database call,then replace your field with your new field

router.post('/answers', expressJwt({secret: config.secret}), function (req, res, next) {
    var user = req.user
    var question = req.body.question
    var answer = req.body.answers

    answer.question._id = question._id;

    db.User.update({email: user.email}, {$set: {answers: answer}}, function (err, doc) {
        if (err) {
            console.error('problem updating answers object', err)
            return res.json(err)
        }
        console.log(doc)
        return res.json('successfully updated answers')
    })
})

answered Sep 5, 2015 at 4:41

Prabjot Singh

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1 Comment

user137717 Over a year ago

yea, this is what I did. it's similar to what you wrote, but with an additional db call to get the answers object. I will accept your answer and edit my question with the code.

mscdex · Accepted Answer · 2015-09-05 04:05:21Z

1

Store it in a variable instead of using the literal object syntax:

var $set = {};
$set[answers[question._id]] = answer;
db.User.update({email: user.email}, {$set: $set}, function (err, doc) {
// ...

Also, if you have ES6 features available to you (e.g. a recent version of io.js) you can use the special bracket notation in object literals to achieve the same thing:

db.User.update({email: user.email}, {$set: {[answers[question._id]]: answer}}, function (err, doc) {
// ...

edited Sep 5, 2015 at 4:05

answered Sep 5, 2015 at 3:59

mscdex

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3 Comments

user137717 Over a year ago

The $set method gives me a 500 internal server error and the second method continues to give me 'unexpected token [' and crash the server

user137717 Over a year ago

i have also tried findOneAndUpdate with upsert: true as mentioned in other SO posts, but no luck. I have updated my post with the full route I'm working on.

user137717 Over a year ago

I must not have ES6 features because the 500 error was coming from the $set[answers...] = answers line.

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