how to update value in mongodb mongoose code example

Example 1: mongoose find and update prop

var query = {'username': req.user.username};
req.newData.username = req.user.username;

MyModel.findOneAndUpdate(query, req.newData, {upsert: true}, function(err, doc) {
    if (err) return res.send(500, {error: err});
    return res.send('Succesfully saved.');
});

Example 2: update query in mongoose

var conditions = { name: 'bourne' } 
  , update = { $inc: { visits: 1 }}

Model.update(conditions, update, { multi: true }).then(updatedRows=>{
  
}).catch(err=>{
  console.log(err)
  
})