Question

I have a problem with embedded document update.

My defined Schemas:

var Talk = new Schema({
    title: {
        type: String,
        required: true
    },
    content: {
        type: String,
        required: true
    },
    date: {
        type: Date,
        required: true
    },
    comments: {
        type: [Comments],
        required: false
    },
    vote: {
        type: [VoteOptions],
        required: false
    },
});

var VoteOptions = new Schema({
    option: {
        type: String,
        required: true
    },
    count: {
        type: Number,
        required: false
    }
});

Now I would like to update vote.count++, with given Talk id and VoteOption id. I have the following function to do the job:

function makeVote(req, res) {

    Talk.findOne(req.params.id, function(err, talk) {
        for (var i = 0; i < talk.vote.length; i++) {
            if (talk.vote[i]._id == req.body.vote) {
                talk.vote[i].count++;

            }
        }
        talk.save(function(err) {
            if (err) {
                req.flash('error', 'Error: ' + err);
                res.send('false');
            } else {
                res.send('true');
            }
        });
    });
}

Everything executes, I get back the res.send('true'), but the value on count does not change.

When I did some console.log I saw that it changed the value, but the talk.save just doesn’t save it in db.

Also I’m quite unhappy about the cycle just to find _id of embedded doc. In the mongoose documentation I read about talk.vote.id(my_id) but that gives me error of not having an id function.

Answer 1

When updating a Mixed type (which seems to be anything else than a basic type, so that also includes embedded documents), one has to call .markModified on the document. In this case, it would be:

talk.markModified("vote"); // mention that `talk.vote` has been modified

talk.save(function(err) {
    // ...
});

Hope this helps someone in the future since I couldn’t find the answer very quickly.

---

Reference:

… Mongoose loses the ability to auto detect/save those changes. To “tell” Mongoose that the value of a Mixed type has changed, call the .markModified(path) method of the document passing the path to the Mixed type you just changed.