Moongose没有更新嵌套的Arrary

Question

  Datemodel = {
    "_id": "5922f58599ff690ea4ffb4cd",
      "events": [
        {
          "eventDate": "2017-04-30T18:30:00.000Z",
          "eventName": "Project Name",
          "_id": "591e953982c0423238721b09"
        },
        {
          "eventDate": "2017-05-15T18:30:00.000Z",
          "eventName": "Project Name",
          "_id": "591e953982c0423238721b08"
        },
        {
          "eventDate": "2017-05-29T18:30:00.000Z",
          "eventName": "Project Name",
          "_id": "591e953982c0423238721b07"
        }
      ]
    }

我想更新eventName的值，其event._ID是591e953982c0423238721b09

我已执行以下查询

    router.route('/postPhase')
      .post(function (req, res) {
 var eventID = req.body.eventID
var eventName = req.body.eventName
var query = {
 events._id: eventID
}
dataModal.findOneAndUpdate(query,{$set:{events.$.eventName:"eventName"}},{"new":true},function(err, Data){
res.json(data)

})

})

请帮我把数据更新到数据库中