MongoTemplate：符合特定条件的文档的键值求和

Question

我的以下 mongodb 查询按预期工作

db.importedDataItems.aggregate({
    $match: {
        mobile: "1234567890"
    }
}, {
    $group: {
        _id: 'mobile',
        calls: { $sum: '$calls' }
    }
 })

但即使在参考 these questions & tutorial 之后，它的等效 Java 代码...

Aggregation agg = Aggregation.newAggregation(Aggregation.match(Criteria.where("mobile").is("1234567890"),
    Aggregation.group("mobile").sum("calls").as("totalCalls"),
    Aggregation.project("totalCalls"));
AggregationResults<Doc> results = mongoTemplate.aggregate(agg, "yoCollection",
    Doc.class);
Doc doc = results.getMappedResults().get(0);

...returns 一个空列表并抛出 IndexOutOfBoundsException 尽管我的查询 returns 在控制台上得到结果！

Answer 1

您缺少 match() 参数的右括号：

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

Aggregation agg = Aggregation.newAggregation(
        match(Criteria.where("mobile").is("1234567890")), // <-- missing closing parenthesis
        group("mobile").sum("calls").as("totalCalls"),
        project("totalCalls")
    );

AggregationResults<Doc> results = mongoTemplate.aggregate(agg, "yoCollection", Doc.class);
Doc doc = results.getMappedResults().get(0);