Upsert

gistfile1.js

adapter.upsert = function (model, id, update) {
  var _this = this;
  model = typeof model == 'string' ? this.model(model) : model;
  update = this._serialize(model, update);
  return new Promise(function (resolve, reject) {
    model.findByIdAndUpdate(id, update,{upsert:true}, function (error, resource) {
      if (error) {
        return reject(error);
      }
      _this._handleWrite(model, resource, error, resolve, reject);
    });
  });
};