gistfile1.txt

/*
 * Any schema with this plugin will run validators on
 * `findOneAndUpdate()` by default.
 */
var runValidatorsPlugin = function(schema, options) {
  schema.pre('findOneAndUpdate', function(next) {
    this.options.runValidators = true;
    next();
  });
};

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

// Attach the plugin to `breakfastSchema`
breakfastSchema.plugin(runValidatorsPlugin);