code: async function many2many (source, model, args = [], t) {
    let pluralModel = pluralize.plural(model)
    let current = []
  
    if (args.every(arg => _.isObject(arg))) {
      for (let arg of args) {
        let obj = await util.insertOrUpdate(this.models[model], arg, t)
  
        if (obj) {
          current.push(obj)
        }
      }
    } else {
      current = await this.models[model].findAll({
        where: {id: {[Op.in]: args}},
        transaction: t
      })
    }
  
    await source[`set${_.upperFirst(this.associations[pluralModel].as)}`](current, {transaction: t})
  }
docs: 查找相关的数据, 更新或者插入
  @param {object} source source model
  @param {string} model target model
  @param {object|array} args 要生成的参数
  @param {any} t 事务标志
  @return {Promise.<void>}
  @this model