code: async function one2one (source, model, args = {}, t) {
    let sourceId = `${this.name}Id`
    let previous = await this.models[model].findOne({
      where: {[sourceId]: source.id},
      transaction: t
    })
  
    if (!args.hasOwnProperty(sourceId)) {
      args[sourceId] = source.id
    }
    let insert = await util.insertOrUpdate(this.models[model], args, t)
  
    if (insert) {
      await previous.update({[sourceId]: null}, {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