我正在尝试使用MyBatis在我的数据模型中映射一对多的关系。这基于以下类:
class Team{
String mId;
String mName;
List<Player> mPlayers;
}
class Player{
String mId;
String mName;
}
我想编写一个返回匹配列表的查询,每个匹配都填充了与该匹配对应的标记。
<select id="getTeams" resultType="Team" resultMap="TeamMap">
SELECT id, name, players.id as player_id, players.name as player_name
FROM teams
JOIN players ON teams.id = players.team_id
</select>
<resultMap type="Team" id="TeamMap">
<id property="mId" column="id"/>
<result property="mName" column="name"/>
<collection property="mTags" javaType="List" ofType="Player">
<id property="player_id" column="mId"/>
<result property="player_name" column="mName"/>
</collection>
</resultMap>
但我遇到的问题是每个Team对象只填充一个Player。如何更改此项以确保每个团队都包含属于它的所有玩家?
答案 0 :(得分:7)
我试图关注这个问题,并且我使用Annotations在Mybatis中创建了一对多关系。以下是我的代码,
<强> UserMapper.java 强>
@Select("SELECT teamId, name FROM TEAM")
@Results(value = {
@Result(property="teamId", column = "teamId"),
@Result(property="name", column = "name"),
@Result(property="players", column="teamId", javaType= List.class, many=@Many(select="selectPlayers"))
})
public List<Team> getAllTeams();
@Select("SELECT * FROM PLAYER WHERE teamId = #{teamId}")
@Results(value={
@Result(property="playerId", column ="playerId" ),
@Result(property="name", column = "name")
})
List<Player> selectPlayers(String teamId);
我的 Team.java :
public class Team {
private Long teamId;
private String name;
private List<Player> players;
//...getters and setters
}
<强> Player.java 强>:
public class Player {
private Long playerId;
private String name;
private Team team;
//...getter and setters
}
<强> team.sql 强>
CREATE TABLE `team` (
`teamId` bigint(10) NOT NULL AUTO_INCREMENT,
`name` varchar(50) DEFAULT NULL,
PRIMARY KEY (`teamId`)
)
<强> player.sql 强>
CREATE TABLE `player` (
`playerId` bigint(10) NOT NULL AUTO_INCREMENT,
`name` varchar(50) DEFAULT NULL,
`teamId` bigint(10) DEFAULT NULL,
PRIMARY KEY (`playerId`),
KEY `FK_TEAM_ID` (`teamId`),
CONSTRAINT `FK_TEAM_ID` FOREIGN KEY (`teamId`) REFERENCES `team` (`teamId`)
)
<强> UserServiceImpl.java 强>
@Autowired
private UserMapper userMapper;
...
/* Get the list of teams with players data */
List<Team> teams = userMapper.getAllTeams();
...
希望这对未来的读者有用。
答案 1 :(得分:2)
找到解决方案。我所要做的就是从#34; id&#34;更改集合中的player_id映射。到&#34;结果&#34;。