我正在尝试将 MongoDB 聚合函数转换为 Java 聚合函数。
我的 MongoDB 查询是
[
{
"$match": {
"indicesId": "VUSSTAPNETFF"
}
},
{
"$unwind": "$dataSets"
},
{
"$match": {
"dataSets.date": {
"$lte": ISODate("2013-12-31T18:30:00.000Z"),
"$gte": ISODate("2008-12-31T18:30:00.000Z")
}
}
},
{
"$group": {
"_id": "$indicesId",
"mean": {
"$avg": "$dataSets.data"
},
"indices": {
"$push": "$$ROOT"
}
}
},
{
"$unwind": "$indices"
},
{
"$project": {
"_id": 1,
"mean": 1,
"firstResult": {
"$multiply": [
{
"$subtract": [
"$indices.dataSets.data",
"$mean"
]
},
{
"$subtract": [
"$indices.dataSets.data",
"$mean"
]
}
]
}
}
},
{
"$group":{
"_id":"",
"secondResult": {
"$avg": "$firstResult"
},
"mean":{
"$first": "$mean"
}
}
},
{
"$project":{
"data":{
"$sqrt":"$secondResult"
},
"mean": "$mean"
}
}
]
我尝试了以下代码在java中进行转换。
BasicDBList subtractDBList= new BasicDBList();
subtractDBList.add("$indices.dataSets.data");
subtractDBList.add("$mean");
BasicDBList multiplyDBList= new BasicDBList();
multiplyDBList.add(new BasicDBObject("$subtract",subtractDBList));
multiplyDBList.add(new BasicDBObject("$subtract",subtractDBList));
Aggregation meanAggregation= Aggregation.newAggregation(Aggregation.match(Criteria.where(IndicesUtil.INDICES_ID).is(indicesId)),
Aggregation.unwind(IndicesUtil.PREFIX+IndicesUtil.DATA_SETS),
Aggregation.match(Criteria.where(IndicesUtil.DATA_SETS_DATE).gte(startDate).lte(indicesDataSet.getDate())),
Aggregation.group(IndicesUtil.INDICES_ID).avg(averageParameter).as(IndicesUtil.MEAN).push("$$ROOT").as("indices"),
Aggregation.unwind(IndicesUtil.PREFIX+IndicesUtil.INDICES),
new AggregationOperation() {
@Override
public DBObject toDBObject(AggregationOperationContext arg0) {
return new BasicDBObject("$project",
new BasicDBObject("_id",1).append("mean", IndicesUtil.PREFIX+IndicesUtil.MEAN).append("firstResult",
new BasicDBObject("$multiply",multiplyDBList)));
}
},
Aggregation.group().avg("$firstResult").as("secondResult").first(IndicesUtil.PREFIX+IndicesUtil.MEAN).as(IndicesUtil.MEAN),
new AggregationOperation() {
@Override
public DBObject toDBObject(AggregationOperationContext arg0) {
return new BasicDBObject("$project",
new BasicDBObject(IndicesUtil.DATA,
new BasicDBObject("$sqrt","$secondResult").append("mean", IndicesUtil.PREFIX+IndicesUtil.MEAN)));
}
}
);
我遇到了以下问题
Aggregation.group().avg("$firstResult").as("secondResult").first(IndicesUtil.PREFIX+IndicesUtil.MEAN).as(IndicesUtil.MEAN),
错误如下
Invalid reference '$firstResult'!
提前致谢。
最佳答案
您可以简化 1.10.1-Release spring mongo 版本上的聚合。您应该避免使用BasicDBObject/Document并使用spring提供的辅助方法。
Aggregation meanAggregation = Aggregation.newAggregation(
Aggregation.match(Criteria.where(IndicesUtil.INDICES_ID).is(indicesId)),
Aggregation.unwind(IndicesUtil.PREFIX+IndicesUtil.DATA_SETS),
Aggregation.match(Criteria.where(IndicesUtil.DATA_SETS_DATE).gte(startDate).lte(indicesDataSet.getDate())),
Aggregation.group(IndicesUtil.INDICES_ID).avg(averageParameter).as(IndicesUtil.MEAN).push("$$ROOT").as("indices"),
Aggregation.unwind(IndicesUtil.PREFIX+IndicesUtil.INDICES),
Aggregation.project("_id", "mean").andExpression("(indices.dataSets.data - mean) * (indices.dataSets.data - mean)").as("firstResult"),
Aggregation.group().avg("$firstResult").as("secondResult").first(IndicesUtil.PREFIX+IndicesUtil.MEAN).as(IndicesUtil.MEAN),
Aggregation.project("mean").and("secondResult").sqrt().as(IndicesUtil.DATA)
);
关于java - 尝试将 mongoDB 聚合查询转换为 java 聚合查询，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/43293094/