Spring Boot使用ReplaceRoot进行MongoDB聚合/如何获取组中的最新项目

import org.springframework.data.mongodb.core.aggregation.Aggregation;
import org.springframework.data.mongodb.core.aggregation.AggregationOperation;
import org.springframework.data.mongodb.core.aggregation.AggregationResults;
import org.springframework.data.mongodb.core.aggregation.GroupOperation;
import org.springframework.data.mongodb.core.aggregation.MatchOperation;
import org.springframework.data.mongodb.core.aggregation.ReplaceRootOperation;
import org.springframework.data.mongodb.core.aggregation.SortOperation;
import org.springframework.data.mongodb.core.query.Criteria;

...

MatchOperation match = Aggregation.match(Criteria.where("field").is("value"));
SortOperation sort = Aggregation.sort(Sort.Direction.DESC, "dateField");
GroupOperation group = Aggregation.group("groupField").first("$$ROOT").as("latest");
ReplaceRootOperation replaceRoot = Aggregation.replaceRoot("latest");

Aggregation aggregation = Aggregation.newAggregation(match, sort, group, replaceRoot);
AggregationResults<Document> results = mongoTemplate.aggregate(aggregation, "collectionName", Document.class);
List<Document> documents = results.getMappedResults();