Question

我有一个订单集合和orderLastStatusChangeDatetime，estimatedDeliveryDatetime和orderPrice都是订单集合的归档名称。我必须获得orderPrice的总和，其中orderLastStatusChangeDatetime小于或等于estimatedDeliveryDatetime。我使用以下查询来获取总记录...

Criteria criteria = new Criteria() {
        @Override
        public DBObject getCriteriaObject() {
            DBObject obj = new BasicDBObject();
            obj.put("$where", "this.orderLastStatusChangeDatetime <= this.estimatedDeliveryDatetime");
            return obj;
        }
    };

    Query query = new Query();


    query.addCriteria(criteria);


    totalOrder = (int) mongoTemplate.count(query,ORDERS_COLLECTION_NAME);

但我必须得到订单价格的总和。我在聚合匹配中使用了相同的标准。但它给出了错误＆＃34;命令失败，错误16395：＆＃39;异常：$ where不允许在$ match聚合表达式中＆＃39;＆＃34;

Answer 1

您可以使用以下聚合管道。在cmp阶段创建$project字段，以保留orderLastStatusChangeDatetime <= estimatedDeliveryDatetime的结果，然后$match，cmp等于true和$group } $sum order price。{/ p>

import static org.springframework.data.mongodb.core.aggregation.Aggregation.*;
import static org.springframework.data.mongodb.core.query.Criteria.where;

Aggregation aggregation = newAggregation(project("orderPrice").andExpression("orderLastStatusChangeDatetime <= estimatedDeliveryDatetime").as("cmp"), match(Criteria.where("cmp").is(true)), group().sum("orderPrice").as("total"));

BasicDBObject results = mongoOperations.aggregate(aggregation, ORDERS_COLLECTION_NAME, BasicDBObject.class).getUniqueMappedResult();
int totalOrder = results.getInt("total");

更新：在1.8.5 RELEASE中使用AggregationExpression

Aggregation agg = newAggregation(
    project("orderPrice").and(new AggregationExpression() {
                @Override
                public DBObject toDbObject(AggregationOperationContext context) {
                    return new BasicDBObject("$lte", Arrays.<Object>asList("$orderLastStatusChangeDatetime", "$estimatedDeliveryDatetime"));
                    }
    }).as("cmp"),
    match(Criteria.where("cmp").is(true)),
    group().sum("orderPrice").as("total")
);

Answer 2

你可以在这里找到很多如何使用它的例子： https://www.javatips.net/api/spring-data-mongodb-master/spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/aggregation/ProjectionOperationUnitTests.java

spring mongodb聚合比较两个字段并获得一列的总和

2 个答案: