[英]How to reuse MyBatis's mapper in another mapper?
我有表event
和message
,它们具有一对一的关系,并由类表示:
public class Event {
private Long id;
private Message message;
}
public class Message {
private Long id;
}
并且有两个映射器: EventMapper
和MessageMapper
:
public interface EventMapper {
@Select("SELECT * FROM event WHERE date BETWEEN #{from} AND #{to}")
@Results({
@Result(property = "id", column = "id"),
@Result(property = "message", column = "message_id",
javaType = Message.class, one = @One(select = "getMessage"))
})
List<Event> selectInInterval(@Param("from") Date from, @Param("to") Date to);
@Select("SELECT * FROM message WHERE id = #{id}")
Message getMessage(@Param("id") Long id);
}
public interface MessageMapper {
@Select("SELECT * FROM message WHERE id = #{id}")
@Results({
@Result(property = "id", column = "id"),
@Result(property = "text", column = "text")
})
List<Event> selectById(@Param("id") Long id);
}
EventMapper
选择事件并通过注释使用getMessage
来选择和映射事件的消息,并将其映射。 但是我已经在MessageMapper
拥有相同的方法selectById
,因此可以重用它吗?
为了使用来自其他映射器的任何定义(包括语句或ResultMap
您应将映射器的名称namespace
(完全限定名称)包括在该实体的标识符中。
在您的示例中,假设MessageMapper
位于com.company.app.mappers
软件包中,则它将为:
public interface EventMapper {
@Select("SELECT * FROM event WHERE date BETWEEN #{from} AND #{to}")
@Results({
@Result(property = "id", column = "id"),
@Result(property = "message", column = "message_id",
javaType = Message.class,
one = @One(select = "com.company.app.mappers.MessageMapper.getMessage"))
})
List<Event> selectInInterval(@Param("from") Date from, @Param("to") Date to);
}
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