解决Mybatis及MP出现返回的Map缺字段的问题

问题描述：

select gantryId as "gantryId",name as "tollStationName",roadId as "roadId",countyName as "countyName",cityName as "cityName" 
from doorframedata where gantryId = "123456"

List> getTollStationData(String gantryId);

因为数据库的原因出现：

        {
            "gantryId": "123456",
            "cityName": "天津市",
            "tollStationName": "xxx收费站名",
            //该处本应该显示 "roadId": "",
            "countyName": "北辰区"
        }

解决方法：
修改yml文件中Mybatis的配置，设置call-setters-on-nulls为true。

例如：

#MR配置
mybatis-plus:
  #mappers文件存放位置
  mapperLocations: classpath:mapper/*.xml
  #配置MR在控制台输出日志
  configuration:
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl
    map-underscore-to-camel-case: false
    #解决Mybatis 查询返回类型为Map 空值字段不显示
    call-setters-on-nulls: true