CODE EXAMPLE FOR JAVASCRIPT

Mongoose UPDATE push

// Add a movie to a user's list of favorites
app.post('/users/:Username/movies/:MovieID', (req, res) => {
  Users.findOneAndUpdate({ Username: req.params.Username }, {
     $push: { FavoriteMovies: req.params.MovieID }
   },
   { new: true }, // This line makes sure that the updated document is returned
  (err, updatedUser) => {
    if (err) {
      console.error(err);
      res.status(500).send('Error: ' + err);
    } else {
      res.json(updatedUser);
    }
  });
});