from_city_id始终写不进去，post过来的值为8：

代码

$model = \Common\Plugin\Db::M('XcxMsgRecord');
        $data['from'] = I('post.from');
        $data['from_name'] = I('post.from_name');
        $data['from_avatar'] = I('post.from_avatar');
        $data['from_city_id'] = I('post.from_city_id');
        $data['target'] = I('post.target');
        $data['content'] = I('post.content');
        $data['create_time'] = I('post.create_time');
        $data['teacher_id'] = I('post.teacher_id');
        $data['teacher_name'] = I('post.teacher_name');
        $data['teacher_avatar'] = I('post.teacher_avatar');
        $data['jmsg_id'] = I('post.jmsg_id');
        $data['wx_xcx_form_id'] = I('post.wx_xcx_form_id');
        $id = $model->add($data);
        if($id){
            $this->httpSuccess($id, '消息入库成功');
        }else{
            $this->httpError('消息入库失败');
        }

数据表

CREATE TABLE `xcx_msg_record` (
  `id` bigint(20) unsigned NOT NULL AUTO_INCREMENT,
  `from` char(25) NOT NULL DEFAULT '' COMMENT '发送方jmessage帐号',
  `from_name` char(25) NOT NULL DEFAULT '',
  `from_avatar` varchar(500) NOT NULL DEFAULT '',
  `from_city_id` char(11) NOT NULL DEFAULT '' COMMENT 'from所在城市',
  `target` char(25) NOT NULL DEFAULT '' COMMENT '接收方jmessage帐号',
  `content` varchar(1000) NOT NULL DEFAULT '' COMMENT '聊天内容，最多1000个字',
  `create_time` int(11) unsigned NOT NULL DEFAULT '0',
  `teacher_id` int(11) unsigned NOT NULL DEFAULT '0' COMMENT '教员id',
  `teacher_name` char(25) NOT NULL DEFAULT '',
  `teacher_avatar` varchar(500) NOT NULL DEFAULT '',
  `jmsg_id` bigint(20) unsigned NOT NULL DEFAULT '0' COMMENT 'jmessage生成的id',
  `wx_xcx_form_id` char(32) NOT NULL DEFAULT '' COMMENT '微信小程序form_id',
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=25 DEFAULT CHARSET=utf8 ROW_FORMAT=DYNAMIC COMMENT='聊天记录表';