{ jobTitle: '',
  lastPosition: '',
  email: '',
  city: '',
  accountType: 'helper',
  _id: 5c77883d8db04c921db5f635,
  username: 'here2help',
  __v: 0 }

router.put("/profile/:id", middleware.checkProfileOwnership, function(req, res){

    console.log(req.body.profile);

    Profile.findOneAndUpdate(req.params.id, req.body.profile, function(err, updatedProfile){

        if(err){
            console.log(err.message);
            res.redirect("/profile");
        } else {
            console.log(updatedProfile);
            res.redirect("/profile/" + req.params.id);
        }

    });
});

{ accountType: 'helper',
  username: 'here2help',
  email: 'helpingU@me.com',
  city: 'New York',
  jobTitle: 'CEO',
  lastPosition: 'sales rep'}

{ jobTitle: '',
  lastPosition: '',
  email: 'helpingu@me.com',
  city: 'New York',
  accountType: 'helper',
  _id: 5c77883d8db04c921db5f635,
  username: 'here2help',
  __v: 0 }

var mongoose = require("mongoose");
var passportLocalMongoose = require("passport-local-mongoose");

var profileSchema = new mongoose.Schema({
    username: String,
    complete: { type: Boolean, default: false },
    email: { type: String, default: "" },
    city: { type: String, default: "" }
}, { discriminatorKey: 'accountType' });

profileSchema.plugin(passportLocalMongoose);

module.exports = mongoose.model("Profile", profileSchema);

var Profile = require('./profile');

var Finder = Profile.discriminator('finder', new mongoose.Schema({
    position: { type: String, default: "" },
    skills: Array
}));

module.exports = mongoose.model("Finder");

var Profile = require('./profile');

var Helper = Profile.discriminator('helper', new mongoose.Schema({
    jobTitle: { type: String, default: "" },
    lastPosition: { type: String, default: "" }
}));

module.exports = mongoose.model("Helper");

Mongoose: profiles.findAndModify({
  _id: ObjectId("5c78519e61f4b69da677a87a")
}, [], {
  '$set': {
    email: 'finder@me.com',
    city: 'New York',
    accountType: 'helper',
    username: 'User NAme', __v: 0 } }, { new: true, upsert: false, remove: false, projection: {} })

profiles.findAndModify({
  accountType: 'helper',
  _id: ObjectId("5c78519e61f4b69da677a87a")
}, [], {
  '$set': {
    jobTitle: 'CTO',
    email: 'finder@me.com',
    city: 'New York',
    accountType: 'helper ',
    username: 'User Name', __v: 0 } }, { new: true, upsert: false, remove: false, projection: {} })

app.put("/profile/:id", function(req, res){
console.log(req.body);

if(ObjectId.isValid(req.params.id)) {

  switch(req.body.accountType) {
    case 'helper':
    schema = Helper;
    break;
    case 'finder':
    schema = Finder;
    break;
    default:
    schema = Profile;
  }

  schema.findOneAndUpdate({ _id: req.params.id }, { $set : req.body }, { new: true, upsert: false, remove: {}, fields: {} }, function(err, updatedProfile){
      if(err){
          console.log(err);
          res.json(err);
      } else {
          console.log(updatedProfile);
          res.json(updatedProfile);
      }

  });
} else {
  res.json({ error: "Invalid ObjectId"});
} });

db.profile.findOneAndUpdate({ _id: req.params.id }, { $set : req.body }, { new: true, upsert: false, remove: {}, fields: {} }, function(err, updatedProfile){
              if(err) {
                res.json(err);
              } else {
                console.log(updatedProfile);
                res.json(updatedProfile);
              }
          });

Profile.findOneAndUpdate(
  req.params.id,
  req.body.profile,
  {
    returnNewDocument: true
  },
  function(err, updatedProfile) {
    // ...