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我一直在努力编写将 mongo shell 命令转换为 java mongo 驱动程序之上的 java 查询，以便在我的 webapp 项目中调用它：命令如下：

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 中输出以下格式：

{
"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
 }

我使用 java mongo driver 在 java 中编写相同的查询失败。以下是我的查询：

           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;

它返回下面的结果集：

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

我在查询包括分钟部分和小时部分时遇到了挑战。如何调整我的查询以输出与 mongo shell 中相同的结果集。

谢谢你看那个

4

1 回答 1

1

给定查询的 Java 代码如下：

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");
    }
}
于 2013-10-08T12:20:47.777 回答