hapijs joi验证，验证大于其他属性的总和

const Joi = require('joi');

const schema = Joi.object({
  value1: Joi.number().required(),
  value2: Joi.number().required(),
  total: Joi.number().required().valid(Joi.ref('value1').add(Joi.ref('value2')))
});

const data = {
  value1: 5,
  value2: 3,
  total: 8
};

const result = schema.validate(data);
console.log(result);