mybatis一对多查询注解方式

港控/mmm° 2022-04-13 09:24 417阅读 0赞

三层数据结构如下

{
        "code": 1,
        "data": {
            "projectID": 1,
            "projectStageList": [
                {
                    "stageID": 1,
                    "projectID": 1,
                    "stageName": "第一阶段",
                    "taskList": [
                        {
                            "mangerID": 31,
                            "taskName": "学习客服基本职责",
                            "taskID": 1066224890860171264,
                            "stageID": 1
                        },
                        {
                            "mangerID": 19,
                            "taskName": "直通车优化内容",
                            "taskID": 1066229261945696256,
                            "stageID": 1
                        }
                    ]
                },
                {
                    "stageID": 2,
                    "projectID": 1,
                    "stageName": "第二阶段",
                    "taskList": []
                },
                {
                    "stageID": 5,
                    "projectID": 1,
                    "stageName": "看待歌手陈羽凡吸毒被抓一事",
                    "taskList": []
                }
            ]
        },
        "success": true,
        "info": "default info"
    }

简而言之，一个项目有多个阶段，一个阶段有多个任务

One

package cn.com.suntree.cmp.entity;
    
    import com.baomidou.mybatisplus.annotations.TableField;
    import com.baomidou.mybatisplus.annotations.TableId;
    import com.baomidou.mybatisplus.annotations.TableName;
    import com.baomidou.mybatisplus.enums.IdType;
    import lombok.Data;
    
    import java.util.List;
    
    
    @Data
    @TableName("t_cmp_project")
    public class CmpProject {
    
        @TableId(value = "projectID",type = IdType.AUTO)
        @TableField("projectID")
        private Long projectID;
        @TableField("projectName")
        private String projectName;
        private List<CmpProjectStage> projectStageList;//阶段
      
    
    }

many

package cn.com.suntree.cmp.entity;
    
    import com.baomidou.mybatisplus.annotations.TableField;
    import com.baomidou.mybatisplus.annotations.TableId;
    import com.baomidou.mybatisplus.annotations.TableName;
    import com.baomidou.mybatisplus.enums.IdType;
    import lombok.Data;
    
    import java.io.Serializable;
    import java.util.List;
    import java.util.Map;
    
    
    @Data
    @TableName("t_cmp_project_stage")
    public class CmpProjectStage implements Serializable {
    
        @TableId(value = "stageID",type = IdType.AUTO)
        @TableField("stageID")
        private Long stageID;//阶段编号
        @TableField("projectID")
        private Long projectID;//项目编号
        List<Map<Object,Object>> taskList;//关联任务
    }

one 方mapper

@Select("select * from "+tableName+" where projectID = #{projectID}")
        @Results({
                @Result(property = "projectStageList", column = "projectID",id = true,many = @Many(select = "cn.com.suntree.cmp.mapper.CmpProjectStageMapper.getStageListByProjectID"))
        })
        CmpProject getProjectByProgectID(Long projectID);

many方mapper

@Select("select * from "+tableName+" where projectID = #{projectID}")
        @Results({
                @Result(property = "stageID",column = "stageID"),
                @Result(property = "taskList",id = true,column = "stageID", many = @Many(select = "cn.com.suntree.cmp.mapper.MissionTaskMapper.getTaskListByStageID"))
        })
        List<CmpProjectStage> getStageListByProjectID(Long projectID);

最里层mapper

@Select("Select t.stageID AS stageID,t.taskID,t.taskName,t.mangerID,t.mangerName from "+tableName +" t where stageID = #{stageID}")
    	List<Map<Object,Object>> getTaskListByStageID(Long stageID);

有个需要注意的地方 ，就是many方mapper的`@Result(property = "stageID",column = "stageID")`如果不加，第二层的关联id会是null