user is a Mongoose entity object. I want to append some data on user, save it and just proceed to next then() after that entity has been successfully saved on DB. So I am doing:

User
  .findOne({ email: req.body.email })
  .then((user) => {
    user.data = ...;
    user = user.save().then(() => user);
    return user;
  })
  .then((user => ... /* continue after user has been saved */ ))

Yet, I am getting a TypeError: Chaining cycle detected for promise and I am not realizing how to solve my requirements.