gistfile1.txt

var breakfastSchema = new mongoose.Schema({
  steak: {
    type: String,
    required: true,
    enum: ['flank', 'ribeye'],
  },
  eggs: {
    type: Number,
    required: true,
    min: 2
  }
});

// Pre hook for `findOneAndUpdate`
breakfastSchema.pre('findOneAndUpdate', function(next) {
  this.options.runValidators = true;
  next();
});

var Breakfast = db.model('breakfast', breakfastSchema, 'breakfasts');

var updates = { $set: { steak: 'ribeye', eggs: 1 } };
// Note the lack of the `runValidators` option
Breakfast.findOneAndUpdate({}, updates, function(err) {
  // "ValidationError: Path `eggs` (1) is less than minimum allowed value (2)."
  console.log(err);
});