MongoDB：在数组匹配参数中查找子文档
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MongoDB: Find Subdocument in Array Matching Parameters
提问by Matt Weir
In MongoDB I would like to find a document based on the values of a subdocument meeting certain parameters. Specifically I have a document structured like this:
在 MongoDB 中，我想根据满足某些参数的子文档的值来查找文档。具体来说，我有一个结构如下的文档：
{
name: "test",
data: [{
name: "test1",
start: 0,
end: 2
},
{
name: "test2",
start: 15
end: 18
}]
}
How can I tell MongoDB to only return my document if the start time for a data subdocument is less than 5 and the end time for the same subdocument is greater than 5? Currently, if I do
如果数据子文档的开始时间小于 5 并且同一子文档的结束时间大于 5，我如何告诉 MongoDB 仅返回我的文档？目前，如果我这样做
db.foo.findOne({
'data.start': { $lte: 5 },
'data.end': { $gte: 5 }
})
it will return my document always because 5 is greater than 0 and less than 18. How can I tell MongoDB to only return my document if 5 (or whatever value) is greater than 0 and less than 2 OR greater than 15 and less than 18?
它将始终返回我的文档，因为 5 大于 0 且小于 18。如果 5（或任何值）大于 0 且小于 2 或大于 15 且小于 18，我如何告诉 MongoDB 仅返回我的文档?
回答by Thilo
You want to use $elemMatch.
你想使用$elemMatch。
db.foo.findOne({ data: { $elemMatch : {
start: { $lte: 5 },
end: { $gte: 5 }
}}
})
回答by Arpit Aggarwal
Came across this post thinking of cheating the code which wasn't there ;) So thought of sharing the code snippet in Javausing spring-data-mongodb
看到这篇文章想欺骗不存在的代码 ;) 所以想到在Java使用spring-data-mongodb 时分享代码片段
Mongo mongo = new Mongo("localhost", 27017);
MongoTemplate mongoTemplate = new MongoTemplate(mongo, "db");
Query query = new Query();
query.addCriteria(Criteria.where("data").elemMatch(
Criteria.where("start").lte(5)
.andOperator(Criteria.where("end").gte(5))));
Foo foo = mongoTemplate.findOne(query, Foo.class);
