How to use QueryWrapper.select(columns) in Custom SQL statements in mybatis-plus?

This is my wrapper.

QueryWrapper<Tag> tagQueryWrapper = Wrappers.<Tag>query() .select("name", "count(*) num") .groupBy("name") .orderByDesc("num"); 

This is my mapper.

@Component public interface TagMapper extends BaseMapper<Tag> { @Select("select * from tag left join blog_tag bt on tag.id = bt.tag_id ${ew.customSqlSegment}") List<Tag> selectNameNum(IPage<Tag> page, @Param(Constants.WRAPPER) Wrapper<Tag> queryWrapper); } 

I don't know why this 'select(column...)' doesn't work. The SQL statements it generates are as follows:

select * from tag left join blog_tag bt on tag.id = bt.tag_id GROUP BY name ORDER BY num DESC LIMIT ?,?

please help me, I want to know how to replace the '*' in the SQL statement with select(column...)

1 Answer

Given that Constants.WRAPPER is ew you can use another getter in Wrapper to get the select columns list (similar to how you get customSqlSegment already) like this:

@Component public interface TagMapper extends BaseMapper<Tag> { @Select("select ${ew.sqlSelect} from tag left join blog_tag bt on tag.id = bt.tag_id ${ew.customSqlSegment}") List<Tag> selectNameNum(IPage<Tag> page, @Param(Constants.WRAPPER) Wrapper<Tag> queryWrapper); }