JAVA - mongodb 聚合查询方式三

三、BasicDBObject+脚本语句

java代码实现：BasicDBObject groupIndex = new BasicDBObject();
BasicDBObject distinctQuery = new BasicDBObject();
distinctQuery.put("userId", new BasicDBObject("$in", userIds));//UserIds数组
BasicDBObject initIndex = new BasicDBObject();
initIndex.put("count", 0);//给count赋初值
// 脚本（doc代表数据库的数据.prev代表查询结果//prev.count这里的count就是上一步initIndex的count）
String reduce = "function(doc, prev) {if(doc.status==0){prev.count+= 1;};}";
List<Map<String, Object>> basicDBList = (List<Map<String, Object>>) mongoTemplate.getCollection("Collection")
.group(groupIndex, distinctQuery, initIndex, reduce, null);最后循环遍历List即可得到结果
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