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这是一个创建于 681 天前的主题，其中的信息可能已经有所发展或是发生改变。

这当中 episode 的 id 获取为 null ，请问是哪里出了问题

@Select("select * from Anime t where t.id = #{id}")
@Results({
        @Result(column = "id", property = "id", id = true),
        @Result(column = "local_name", property = "localName"),
        @Result(column = "origin_name", property = "originName"),
        @Result(column = "image_path", property = "imagePath"),
        @Result(column = "type", property = "type", typeHandler = BaseEnumTypeHandler.class),
        @Result(column = "broadcast_time", property = "broadcastTime"),
        @Result(column = "state", property = "state", typeHandler = BaseEnumTypeHandler.class),
        @Result(column = "introduction_path", property = "introductionPath"),
        @Result(column = "update_time", property = "updateTime"),
        @Result(many = @Many(select = "org.watp.anifree.anime.dao.AnimeMapper.getSynthesizeEpisodesInfoByAnimeId"), property = "episodes", column = "id", javaType = ArrayList.class)
})
@CacheEnable(type = CacheType.PRIVATE, desc = "SynthesizeAnimeInfo", dataType = DataType.DATA, privateId = "${anime.id}")
AnimePO getSynthesizeAnimeInfoByPO(AnimePO anime);

@Select("select * from Episode t where t.anime_id = #{anime_id} order by t.ordr")
@Results({
        @Result(column = "anime_id", property = "animeId"),
        @Result(column = "image_path", property = "imagePath"),
        @Result(many = @Many(select = "org.watp.anifree.anime.dao.AnimeMapper.getSynthesizePlaysInfoByEpisodeId"), property = "plays", column = "id", javaType = ArrayList.class)
})
List<EpisodePO> getSynthesizeEpisodesInfoByAnimeId(@Param("anime_id") String anime_id);

@Select("select * from Play t where t.episode_id = #{episode_id} order by t.ordr")
@Results({
        @Result(column = "episode_id", property = "episodeId"),
        @Result(column = "type", property = "type", typeHandler = BaseEnumTypeHandler.class)
})
List<PlayPO> getSynthesizePlaysInfoByEpisodeId(@Param("episode_id") String episode_id);

7 条回复

77yf77yf77yf

2023-01-03 19:54:21 +08:00

create table Anime
(
id varchar(16),
local_name varchar(500) not null,
origin_name varchar(500) not null,
image_path varchar(500) not null,
type char(1) not null,
broadcast_time date not null,
author varchar(50),
producer varchar(50),
state char(1) not null,
introduction_path varchar(1000),
update_time datetime not null,
constraint ANIME_ID_PRIMARY primary key (id)
)
create unique index ANIME_LOCALNAME_UNIQUE on Anime(local_name);
create unique index ANIME_ORIGINNAME_UNIQUE on Anime(origin_name);

create table Episode
(
anime_id varchar(16),
id varchar(16),
name varchar(200) not null,
image_path varchar(500),
ordr int not null,
constraint EPISODE_ID_PRIMARY primary key (id),
constraint EPISODE_ANIMEID_FOREIGN foreign key (anime_id) references Anime(id)
)
create unique index EPISODE_NAME_UNIQUE on Episode(name);
create unique index EPISODE_ORDR_UNIQUE on Episode(anime_id,ordr);

create table Play
(
id varchar(16),
episode_id varchar(16),
name varchar(200) not null,
type char(1) not null,
location varchar(500),
ordr int not null,
constraint PLAY_ID_PRIMARY primary key (id),
constraint PLAY_EPISODEID_FOREIGN foreign key (episode_id) references Episode(id)
)
create unique index PLAY_ORDR_UNIQUE on Play(episode_id,ordr);

表结构是这样的

Red998

2023-01-03 20:53:34 +08:00

看到就头疼、为什么要用注解 Results 呢直接写 xml 写 sql 不是更简单。简单直观

77yf77yf77yf

2023-01-03 21:05:41 +08:00

@redorblacck886 我用注解更加习惯一点吧
这个获取到的 episode 对象中 id 为 null,但是后面的 play 对象是根据传过去的 episode id 查出来的，照理来说肯定有，但是就是不知道为什么没有放进对象里

L0L

2023-01-03 21:37:19 +08:00

```java
@Select("select * from Episode t where t.anime_id = #{anime_id} order by t.ordr")
@Results({
@Result(column = "anime_id", property = "animeId"),
@Result(column = "image_path", property = "imagePath"),
@Result(many = @Many(select = "org.watp.anifree.anime.dao.AnimeMapper.getSynthesizePlaysInfoByEpisodeId"), property = "plays", column = "id", javaType = ArrayList.class)
})
List<EpisodePO> getSynthesizeEpisodesInfoByAnimeId(@Param("anime_id") String anime_id);
```
是不是第二条关联语句中的 `column = "anime_id"` 这样呢？
实际是三个表的依次 JOIN 操作，猜测是你第二个语句中实际是没有 column 为 id 的这一列的原因

77yf77yf77yf

2023-01-03 21:46:50 +08:00

@L0L 加了个 id 的 Result 还真的有了，感谢大佬
不是应该实体类和列的名称相同可以自动映射吗，为什么这里需要手写一下，而下面那个 Play 的 id 就不用手写就有，向大佬请教一下

L0L

2023-01-03 21:54:07 +08:00

@77yf77yf77yf 这块可以 debug 看一下，我记得自动映射在 xml 里可以使用双引号实现；注解的方式平常用的比较少，如果是对比 xml 中 resultMap 的标签形式的话，其实你第二个语句实际相当于只使用了你定义的几个 Result 注解的字段，而其他的框架并没有使用，也就没有映射了；

L0L

2023-01-03 21:54:21 +08:00

V 友多说一嘴，一般如果是应用工程中的代码的话，` select * ` 的这种写法尽量还是避免，用到什么写什么，对于后续扩展表的字段结构甚至是查询速度来说，都会有一些提升。