MongoDB：如何使用Java驱动程序使用Mongo Date聚合对日期进行分组 [英] MongoDB: how to group by date with mongo date aggregration using java driver

问题描述

为了在我的webapp项目中调用它，我一直在努力将mongo shell命令转换为java mongo驱动程序上的java查询的命令：命令如下：

I have been struggling writing to convert a mongo shell command to java query on top of the java mongo driver in order to call it in my webapp project: the command is as follow:

db.post.aggregate(
{
 $match: { dateCreated:
                {
                  "$gt": new ISODate("2013-08-09T05:51:15.000Z"),
                  "$lt": new ISODate("2013-08-09T05:51:20.000Z")
                }
       }
 },
 { 
  $group: {
    _id: {
        hour: {$hour: "$dateCreated"},
        minute: {$minute: "$dateCreated"},
        second: {$second: "$dateCreated"}   
    },
    cnt: {$sum : 1}
   }
 }
)

上面的查询在mongo shell中产生以下格式：

The query above outputs result in the format below in the mongo shell:

{
"result" : [
    {
        "_id" : {
            "hour" : 5,
            "minute" : 51,
            "second" : 19
        },
        "cnt" : 26
    },
    {
        "_id" : {
            "hour" : 5,
            "minute" : 51,
            "second" : 18
        },
        "cnt" : 29
    },
    {
        "_id" : {
            "hour" : 5,
            "minute" : 51,
            "second" : 17
        },
        "cnt" : 27
    },
    {
        "_id" : {
            "hour" : 5,
            "minute" : 51,
            "second" : 16
        },
        "cnt" : 25
    },
    {
        "_id" : {
            "hour" : 5,
            "minute" : 51,
            "second" : 15
        },
        "cnt" : 16
    }
],
"ok" : 1
 }

我无法使用Java mongo driver在Java中编写相同的查询。以下是我的查询：

I failed in writing the same query in java using java mongo driver . below is my query:

           DBObject matchStart = new BasicDBObject("$match",new BasicDBObject("dateCreated",new BasicDBObject("$gt",startTime).append("$lt",endTime)));
        DBObject field = new BasicDBObject("dateCreated",1);
        field.put("h", new BasicDBObject("$hour","$dateCreated"));
        field.put("m", new BasicDBObject("$minute","$dateCreated"));
        field.put("s", new BasicDBObject("$second","$dateCreated"));

        DBObject project = new BasicDBObject("$project",field);
        DBObject groupField = new BasicDBObject("_id","$s");


        groupField.put("count", new BasicDBObject("$sum",1));
        DBObject group = new BasicDBObject("$group",groupField);

        AggregationOutput output = mongoOperations.getCollection("post").aggregate(matchStart,project,group);

        return output;

它返回以下结果集：

{"result" : [ 
    { "_id" : 19 , "count" : 26} , 
    { "_id" : 18 , "count" : 29} , 
    { "_id" : 17 , "count" : 27} , 
    { "_id" : 16 , "count" : 25} , 
    { "_id" : 15 , "count" : 16}
          ] , 
"ok" : 1.0}

I在使查询包括分钟部分和小时部分方面遇到困难。如何调整查询以输出与mongo shell shell中相同的结果集。

I am having challenges making the query include the minute part and the hour part. How can tweak my query to output the same resultset as in the mongo shell one.

感谢您查看

推荐答案

给定查询的Java代码如下：

Java code for given query is as follows :

DBCollection coll = ...

Date startDate = ...
Date endDate = ...

DBObject dateQuery = new BasicDBObject();
dateQuery.put("$gt", startDate);
dateQuery.put("$lt", endDate);

DBObject match = new BasicDBObject();
match.put("dateCreated", dateQuery);

DBObject id = new BasicDBObject();
id.put("hour", new BasicDBObject("$hour", "$dateCreated"));
id.put("minute", new BasicDBObject("$minute", "$dateCreated"));
id.put("second", new BasicDBObject("$second", "$dateCreated"));

DBObject group = new BasicDBObject();
group.put("_id", id);
group.put("cnt", new BasicDBObject("$sum", 1));

AggregationOutput output = coll.aggregate(new BasicDBObject("$match", match), new BasicDBObject("$group", group));

if (output != null) {
    for (DBObject result : output.results()) {
        Integer count = (Integer) result.get("cnt");

        DBObject idObj = (DBObject) result.get("_id");
        Integer hour = (Integer) idObj.get("hour");
        Integer minute = (Integer) idObj.get("minute");
        Integer second = (Integer) idObj.get("second");
    }
}

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