Cannot read property '$elemMatch' of undefined while trying to save data in mongo db using node js

Question

I am getting the error while trying to save following data.

Following is the error:

if (fields[key].$elemMatch) {

                     ^

TypeError: Cannot read property '$elemMatch' of undefined at model.Query._castFields (C:\Users\hp\Documents\node-projects\musicfest1\node_modules\mongoose\lib\query.js:4306:23) at model.Query. (C:\Users\hp\Documents\node-projects\musicfest1\node_modules\mongoose\lib\query.js:1971:23) at model.Query._wrappedThunk [as _findOne] (C:\Users\hp\Documents\node-projects\musicfest1\node_modules\mongoose\lib\helpers\query\wrapThunk.js:16:8) at process.nextTick (C:\Users\hp\Documents\node-projects\musicfest1\node_modules\kareem\index.js:369:33) at process.internalTickCallback (internal/process/next_tick.js:70:11)*

var data = {
  eventid: 'eventezy01',
  eventname: event_name,
  title1: title1,
  title2: title2,
  dateVenue: dateVenue,
  date: date,
  venue: venue,
  hsTicket: hsTicket,
  ticketLink: ticketLink,
  ticketPrice: ticketPrice,
  about_heading: about_heading,
  aboutEvent1: aboutEvent1,
  singer_heading: singer_heading,
  hsSinger: hsSinger,
  sponsor_heading: sponsor_heading,
  hsSponsor: hsSponsor,
  singer: arrSinger,
  sponsors: arrSponsor,
  flocation: flocation,
  femail: femail,
  fcontact: fcontact,
  fbLink: fbLink,
  twitterLink: twitterLink,
  youTubeLink: youTubeLink,
  gPlusLink: gPlusLink,
  instaLink: instaLink,
  color: '#f50136',
  bgImage: 'slider.png',
  font: '"Montserrat", sans-serif'
};  

FestData.findOne({eventid: 'eventezy01'}, data, options, (err, doc) => {
if(err) {
  console.log(err);
}


if(!doc) {

  var festData = new FestData(data);
  festData.save();      
}

Answer 1

This happens because you're passing in data to the second parameter of the findOne method, but that argument is for selecting which fields to include. If the found record doesn't have any one of those fields, it will produce this error. You should supply null as the second argument to findOne instead.

See the docs on findOne