update object inside array that is inside collection

Question

I need to update field "rightAnswer" in object inside array that is inside collection.

How can I change boolean of specific comment to true for right question.

In Angular I pass id of question and id of comment to backend. But on the backend I don't know how to update that field. I use MEAN stack.

Question schema:

var questionSchema = new mongoose.Schema({
    title: {type : String, default : '', trim : true},
    text: {type : String, default : '', trim : true},
    publisher_id: {type : mongoose.Schema.ObjectId, ref : 'User'},
    answers: [{
        body: { type : String, default : '' },
        user: { type : mongoose.Schema.ObjectId, ref : 'User' },
        rightAnswer: { type : Boolean, default: false },
        createdAt: { type : Date, default : Date.now }
    }],
    date  : {type : Date, default : Date.now}
});

My route in express:

  Question.update({_id: req.body.question._id}, {"answers._id": req.body.answer._id}, {$set: {"answers.$.rightAnswer": true} }, function(req, data){
    res.json(data);
  });

Solution:

Question.update({_id: req.body.question._id, 
                "answers": {$elemMatch: {_id: req.body.answer._id}}},
                {$set: {"answers.$.rightAnswer": true}}, 
                function(req, res){});

Answer 1

Question.update({_id: req.body.question._id, 
                "answers": {$elemMatch: {_id: req.body.answer._id}}},
                {$set: {"answers.$.rightAnswer": true}}, 
                function(req, res){});