code: function includeHandler (k, v) {
    let mds = k.split('.')
    let field = mds.pop()
  
    _includeModel.call(this, this.options.include, mds, field, v)
  }
docs: 针对 include 表的 where 参数设置
  如果 include 里面有, 查询字段会置入 wherestr 中
  如果没有, 会新建一个 model
  include 处理 2.0版
  
  @param {string} k, key
  @param {string} v, value
  @return {void}
  @inner
  @this Model