MyBatis-Plus Type handler was null on parameter mapping for property '__frch_value1_1.arg'.

当前使用版本(必填,否则不予处理)

mybatis-plus: 3.5.3.1

该问题是如何引起的

保存对象时无法保存，对象属性中存在Map并已经自定义了TypeHandler转成json来保存，出现以下错误

重现步骤

xml:

<mapper namespace="com.device.tdengine.tsmapper.TdengineRequestMapper">

    <insert id="insertBatch">
        insert into
        <foreach collection="datas" index="key" item="value">
            device_request_${value.tag.deviceId} using super_device_request TAGS (#{value.tag.deviceId},#{value.tag.productId},#{value.tag.func}) VALUES
            <foreach collection="value.datas" item="value1" separator=" ">
                (#{value1.ts},#{value1.messageId},#{value1.arg,jdbcType=VARCHAR})
            </foreach>
        </foreach>
    </insert>
</mapper>

pojo

保存的对象DeviceRequestDataTag

@Getter
@Setter
public class DeviceRequestDataTag {
    DeviceRequestTag tag;
    List<DeviceRequest> datas;
}

@Getter
@Setter
@TableName(value = "super_device_request",autoResultMap = true)
public class DeviceRequest implements Serializable {
    String messageId;
    Long deviceId;
    Long productId;
    String func;
    @TableField(value = "arg", typeHandler = MapTypeHandler.class,jdbcType = JdbcType.VARCHAR)
    Map<String,Object> arg;
    Timestamp ts;
}


@MappedTypes({Map.class})
@MappedJdbcTypes(JdbcType.VARCHAR)
public class MapTypeHandler extends AbstractJsonTypeHandler<Map> {
    Class<?> type;

    public MapTypeHandler(Class<?> type) {
        this.type = type;
    }
    @Override
    protected Map parse(String json) {
        if(StrUtil.isNotEmpty(json)){
            return JSONUtil.toBean(json,Map.class);
        }else{
            return null;
        }

    }
    @Override
    protected String toJson(Map obj) {
        return JSONUtil.toJsonStr(obj);
    }
}

报错信息

··· org.mybatis.spring.MyBatisSystemException: nested exception is org.apache.ibatis.exceptions.PersistenceException:

Error updating database. Cause: java.lang.IllegalStateException: Type handler was null on parameter mapping for property '__frch_value1_1.arg'. It was either not specified and/or could not be found for the javaType (java.util.Map) : jdbcType (VARCHAR) combination.

The error may exist in file [D:\webproject\nacos-device\device-data\tdengine-component\target\classes\tsmapper\TdengineDeviceRequestMapper.xml]

The error may involve com.device.tdengine.tsmapper.TdengineRequestMapper.insertBatch

The error occurred while executing an update

Cause: java.lang.IllegalStateException: Type handler was null on parameter mapping for property '__frch_value1_1.arg'. It was either not specified and/or could not be found for the javaType (java.util.Map) : jdbcType (VARCHAR) combination.

at org.mybatis.spring.MyBatisExceptionTranslator.translateExceptionIfPossible(MyBatisExceptionTranslator.java:96)
at org.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:441)
at com.sun.proxy.$Proxy129.insert(Unknown Source)
at org.mybatis.spring.SqlSessionTemplate.insert(SqlSessionTemplate.java:272)

··· 你好，在保存对象时，MapTypeHandler 不会触发tojson 是哪里写错了吗？非常感谢🙏

Comment From: tom055

已解决，用BaseTypeHandler去实现