博客

import org.springframework.data.mongodb.core.MongoTemplate;

import org.springframework.data.mongodb.core.aggregation.Aggregation;

import org.springframework.data.mongodb.core.aggregation.AggregationResults;

import org.springframework.data.mongodb.core.aggregation.TypedAggregation;

第一种，使用mongoTemplate.findDistinct去重，不支持排序，即使你的query条件带sort排序方法。mongoTemplate.findDistinct去重，会使排序失效。优点：查询效率高

缺点：只返回单一字段。不知多字段返回。不能使用排序，不推挤使用

Query query = new Query();

query.addCriteria(Criteria.where(“deviceId”).is(getListParam.getDeviceId())).with(Sort.by(Sort.Order.desc(“startDate”)));

List list = mongoTemplate.find(query, RedPacketDeviceRelation.class);

List activeCodes = mongoTemplate.findDistinct(query, “activeCode”, “redPacketDeviceRelation”,RedPacketDeviceRelation.class, RedPacketDeviceRelation.cla