mongodb操作
Criteria cri = Criteria.where("schoolId").is(gxyJobEntity.getShoolId());
Aggregation agg = Aggregation.newAggregation( Aggregation.match(cri), Aggregation.project("memberId","attendenceTime","address"), Aggregation.group("memberId").max("attendenceTime").as("attendenceTime") ); List<MongoMoguAttendenceDto> result =template.aggregate(agg,"mogu_attendance",MongoMoguAttendenceDto.class).getMappedResults();
mongdb 查询:
db.mogu_attendance.aggregate([
{ "$match":{ "schoolId" : "f11c8ea12f457dbc19c768a8bb6357f8"}} ,
{ "$project":{address:1,memberId:1,attendenceTime:1, schoolId:1,userId:1}},
{ "$group" : { "_id" : "$memberId" ,"attendenceTime" : { "$max" : "$attendenceTime"}}}])
类似于: select memberId as _id , max(attendenceTime) as attendenceTime from mogu_attendance group by memberId where schoolId='f11c8ea12f457dbc19c768a8bb6357f8';
查询某个学校 每个学生(memberId是学生id) 最后一次考勤的时间。
输出:
/* 1 */ { "_id" : "ffd56c4f63f20adbbc7c88fe6dc26353", "attendenceTime" : ISODate("2019-08-31T10:00:00.000Z") } /* 2 */ { "_id" : "11c21ada808fb8a9bcb32aade1a5b61e", "attendenceTime" : ISODate("2019-08-22T05:59:28.646Z") }
在实体类
MongoMoguAttendenceDto
总包括两个字段:
public class MongoMoguAttendenceDto implements Serializable { private static final long serialVersionUID = 1L; /** * 唯一主键 */ @Id private String attendanceId; /** * 用户id */ private String userId; …… /** * 考勤时间 */ private Date attendenceTime; private String backup;
则把 查询结果的 _id 取值 memberId , 作为主键,并且 映射给 MongoMoguAttendenceDto 实体对象的 attendanceId ,
max("attendenceTime").as("attendenceTime") 把 attendenceTime字段 映射给 MongoMoguAttendenceDto 实体 的attendenceTime字段
select * from mogu_attendance where memberId='edcff6ee12daf586a27f7ad6cdb9814f' order by attendenceTime desc limit 1;
相当于:
db.getCollection('mogu_attendance').find({ "memberId" : "edcff6ee12daf586a27f7ad6cdb9814f"}).sort({"attendenceTime":-1}).limit(1)
java语句:
Sort sort =null; sort = new Sort(Sort.Direction.DESC,"attendenceTime"); Query query = new Query(); Criteria cri = Criteria.where("memberId").is(gxyJobEntity.getStudentId()); query.addCriteria(cri); List<MongoMoguAttendenceDto> result =template.find(query.with(sort).limit(1),MongoMoguAttendenceDto.class);
或者:MongoMoguAttendenceDto result =template.findOne(query.with(sort).limit(1),MongoMoguAttendenceDto.class);