$set no mongoose code example

Example 1: create document mongoose

var Tank = mongoose.model('Tank', yourSchema);

var small = new Tank({ size: 'small' });
small.save(function (err) {
  if (err) return handleError(err);
  // saved!
});

// or

Tank.create({ size: 'small' }, function (err, small) {
  if (err) return handleError(err);
  // saved!
});

// or, for inserting large batches of documents
Tank.insertMany([{ size: 'small' }], function(err) {

});

Example 2: findone and update mongoose

// Using queries with promise chaining
Model.findOne({ name: 'Mr. Anderson' }).
  then(doc => Model.updateOne({ _id: doc._id }, { name: 'Neo' })).
  then(() => Model.findOne({ name: 'Neo' })).
  then(doc => console.log(doc.name)); // 'Neo'

// Using queries with async/await
const doc = await Model.findOne({ name: 'Neo' });
console.log(doc.name); // 'Neo'