mongodb mongotemplate聚合

1.group by并且计算总数

　　@Test
    public void insertTest() {
        //测试数据
        //insertTestData();
        Aggregation agg = Aggregation.newAggregation(
                //Aggregation.match(Criteria.where("groupId").is(5)),
                Aggregation.group("groupId").count().as("total"),
                Aggregation.project("total").and("groupId").previousOperation(),
                Aggregation.sort(Sort.DEFAULT_DIRECTION, "total"));
        List<StaCount> list = mongoTemplate.aggregate(agg, "currentUser", StaCount.class).getMappedResults();
        for(StaCount count : list) {
            System.out.println(count.getGroupId() + ":" + count.getTotal());
        }
　　｝
如果要带其他字段，将红字变为 Aggregation.group("groupId","groupName"...),并将project的and部分去掉即可;

2.Crieria的使用，注意andOperator和orOperator的用法

Aggregation agg = Aggregation.newAggregation(

　　　　Aggregation.match(new Criteria()

　　　　　　　　　　　　.andOperator(Criteria.where("onlineTime").gt(new Date()))

　　　　　　　　　　　　.orOperator( Criteria.where("offlineTime").gt(new Date())

　　　　,Criteria.where("offlineTime").exists(false) ))

3.Query的排序和分页

Query query = new Query(Criteria.where(ReportField.GROUP_ID).in(groupIdList));
        query.with(new Sort(Direction.DESC, ReportField.ID));
        query.skip(lastId).limit(limit);