问题描述

我有一个 MongoDB 存储来自不同传感器的数据.它的结构如下:

I have a MongoDB storing data from different sensors. It has the following structure:

 {
     "_id" : 1,
     "sensorName" : "Heart Rate",
     "samplePeriod" : 1000,
     "data" : [
             {
                 "timestamp" : NumberLong("1483537204046"),
                 "dataPoints" : [ 68 70 ]
             },
             {
                 "timestamp" : NumberLong("1483537206046"),
                 "dataPoints" : [ 68 70 ]
             }
     ]
}
{
    "_id" : 2,
    "sensorName" : "Ambient Light",
    "samplePeriod" : 500,
    "data" : [
            {
                "timestamp" : NumberLong("1483537204058"),
                "dataPoints" : [ 56, 54, 54, 54 ]
            },
            {
                "timestamp" : NumberLong("1483537206058"),
                "dataPoints" : [ 56, 54, 54, 54 ]
            }
    ]
}

例如，现在我需要心率" - 包含所有字段及其数据"字段的文档 - 匹配条件时间戳在 1483537204000 和 1483537214000 之间"的子文档.

Now for example i need the "Heart Rate" - document with all of its fields and those of its "data" - subdocuments matching the condition "timestamp between 1483537204000 and 1483537214000".

我已经在另一个问题中得到了关于如何在 mongo shell 中执行此操作的答案.请参阅此代码:

I already got the answer on how to do this in the mongo shell in another Question. See this code:

aggregate([{
    $match: {
        "_id": 1
    }
}, {
    "$project": {
        "_id": 1,
        "sensorName": 1,
        "samplePeriod": 1,
        "data": {
            "$filter": {
                "input": "$data",
                "as": "result",
                "cond": {
                    $and: [{
                        $gte: ["$$result.timestamp", 1483537204000]
                    }, {
                        $lte: ["$$result.timestamp", 1483537214000]
                    }]
                }
            }
        }
    }
}])

但是我如何在 java spring-data 中做到这一点?spring-data 中似乎没有像 $filter 这样的东西.有解决办法吗?

But how do I do this in java spring-data? It seems there is nothing like $filter in spring-data. Is there a workaround?

$filter 的效率如何?您能想出一种更有效/更实用的方式在 mongodb 中构建此类数据吗?

How efficient is $filter anyway? Can you think of a more efficient/practical way of structuring this kind of data in mongodb?

提前致谢！

推荐答案

你需要使用spring mongo数据依赖中提供的MongoTemplate.当前发行版本中没有对 $filter 的开箱即用支持.使用 AggressionExpression.在项目中包括以下投影.使用 1.8.5 spring mongo 数据版本.

You'll need to make use of MongoTemplate provided in the spring mongo data dependency. There is no out of box support for $filter in the current release version. Make use of AggressionExpression. Include below projection in project. Use 1.8.5 spring mongo data version.

Aggregation aggregation = newAggregation(
        match(Criteria.where("_id").is(1)),
        project( "_id", "sensorName", "samplePeriod").and(new AggregationExpression() {
            @Override
            public DBObject toDbObject(AggregationOperationContext aggregationOperationContext) {
                DBObject filter = new BasicDBObject("input", "$data").append("as", "result").append("cond",
                        new BasicDBObject("$and", Arrays.<Object> asList(new BasicDBObject("$gte", Arrays.<Object> asList("$$result.timestamp", 1483537204000L)),
                                new BasicDBObject("$lte", Arrays.<Object> asList("$$result.timestamp", 1483537214000L)))));
                return new BasicDBObject("$filter", filter);
            }
        }).as("data")
);

List<BasicDBObject> dbObjects = monoTemplate.aggregate(aggregation, "collectionname", BasicDBObject.class).getMappedResults();

这篇关于在mongodb中查询一个文档及其所有匹配条件的子文档(使用spring)的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持跟版网！