User callback

UserCallback.js

exports.createOrAddUser = (req, res, next) => {
  User.findUser(req.body, (err, data) => {
    if (err) {
      return next(err)
    };

    if (data) {
      const existingUser = new User(data);
      existingUser.update(req.body, (err, data) => {
        if (err) {
          return next(err);
        }

        return res.send(data);
      });
    }

    const newUser = new User();
    newUser.addUser(req.body, (err, data) => {
      if (err) {
        return next(err);
      }
      return res.send(data);
    })
  })
}