MongoDB-猫鼬$ inc在文档数组内的对象

Question

So I am trying to update the value of an object inside an array inside a document. The Schema for the document looks like this:

var pollSchema = new Schema({
  title: String,
  hash: String,
  answers: [{answer: String, votes: Number}]
});

And this is how my current update code looks like:

module.exports.updatePoll = function(socket, data){
  var answerss = 'answers.0.votes';

  hash = data.url.match(/\/([^/]*)$/)[1];
  Poll.findOne({'hash' : hash}, function(err, poll){
    if (err) return handleError(err);
    console.log(poll.answers[data.id])
  });
  Poll.update({hash: hash}, {$inc: {'answers.{data.id}.votes': 1}}, function(err, poll){
    if (err) return console.log(err);
    //socket.emit('updatePoll', hash);
  });

Ive tried pasting answerss in it instead of 'answers.{data.id}.votes' and also tried some other things. It only really works when I directly paste in 'answers.0.votes'. And this is a problem because the data.id can be a value of 0 to 10. I have no idea how I would implement this and the other answers on stackoverflow or google did not give much insight on the problem.

I hope you can help me. Thanks!

Answer 1

You don't need the initial find from what I can tell. You can do it all in one update statement. You need to match the array element you want to update simply by specifying its index:

      var answerKey = 'answers.' + data.id + '.votes';
  var updateJSON = {$inc: {}};
  updateJSON.$inc[answerKey] = 1;
  hash = data.url.match(/\/([^/]*)$/)[1];
  Poll.update({hash: hash}, updateJSON, function(err, poll){
    if (err) return console.log(err);
    //socket.emit('updatePoll', hash);
  });