关于Mybatis-Plus查询Mysql8 json 格式的数据，返回为null问题和插入报错的问题

 数据库字段类型是json

 字段有值，但是查询你后返给前端是null

 插入报错需要添加对应的 typeHandler，可以是框架自带的，也可以是自定义的，自定义的需要注册(@TableField(typeHandler = ListTypeHandler.class))

Error updating database. Cause: java.lang.IllegalStateException: Type handler was null on parameter mapping for property 'xxxxxx'. It was either not specified and/or could not be found for the javaType (java.util.List) : jdbcType (null) combination.\r\n### The error may exist in org/xxxx/modules/userdata/mapper/xxxxMapper.java (best guess)\r\n### The error may involve org.xxxx.modules.userdata.mapper.xxxxxMapper.insert\r\n### The error occurred while executing an update\r\n### Cause: java.lang.IllegalStateException: Type handler was null on parameter mapping for property 'xxxxxx'. It was either not specified and/or could not be found for the javaType (java.util.List) : jdbcType (null) combination.

查询为null：需要把自动映射加上autoResultMap = true，默认是false

 改完配置后再查询