是否可以查询MongoDB文档并将其分组到一个子文档数组中？

Question

我有以下MongoDB的文件：

{ 
    "_id" : ObjectId("58950c9c247430c8d9f3997c"), 
    "stamp_dt" : ISODate("2015-10-15T00:09:00.000+0000"), 
    "start_lat" : 52.49512579479001, 
    "asimId" : ObjectId("588fbe3b835262b7f5ede6f5") 
} 
{ 
    "_id" : ObjectId("58950c9c247430c8d9f3997d"), 
    "stamp_dt" : ISODate("2015-10-15T00:09:00.000+0000"), 
    "start_lat" : 52.48510698285751, 
    "asimId" : ObjectId("588fbe3b835262b7f5ede6f5") 
} 
{ 
    "_id" : ObjectId("58950c9c247430c8d9f3997e"), 
    "stamp_dt" : ISODate("2015-10-15T00:09:00.000+0000"), 
    "start_lat" : 52.49966542235, 
    "asimId" : ObjectId("588fbe3b835262b7f5ede6f5") 
} 
{ 
    "_id" : ObjectId("58950c9c247430c8d9f3997f"), 
    "stamp_dt" : ISODate("2015-10-15T00:09:00.000+0000"), 
    "start_lat" : 52.52645820975653, 
    "asimId" : ObjectId("588fbe3b835262b7f5ede6f5") 
} 

注意，都对stamp_dt相同的值。我需要一种方法来组这些文件是这样的：

{ 
    "stamp_dt" : ISODate("2015-10-15T00:09:00.000+0000"), 
    "results": [ 
     { 
      "_id" : ObjectId("58950c9c247430c8d9f3997c"), 
      "start_lat" : 52.49512579479001, 
      "asimId" : ObjectId("588fbe3b835262b7f5ede6f5") 
     } 
     { 
      "_id" : ObjectId("58950c9c247430c8d9f3997d"), 
      "start_lat" : 52.48510698285751, 
      "asimId" : ObjectId("588fbe3b835262b7f5ede6f5") 
     } 
     { 
      "_id" : ObjectId("58950c9c247430c8d9f3997e"), 
      "start_lat" : 52.49966542235, 
      "asimId" : ObjectId("588fbe3b835262b7f5ede6f5") 
     } 
     { 
      "_id" : ObjectId("58950c9c247430c8d9f3997f"), 
      "start_lat" : 52.52645820975653, 
      "asimId" : ObjectId("588fbe3b835262b7f5ede6f5") 
     } 
    ] 
} 

我可以使用代码做到这一点，但有没有办法通过MongoDB的查询（也许聚集）这样做呢？

Answer 1

你可以尝试下面的东西。

db.collection.aggregate(
    [{ 
     $group: { 
      _id: "$stamp_dt", 
      "data": { 
       $push: { 
        _id: "$_id", 
        start_lat: "$start_lat", 
        asimId: "$asimId" 
       } 
      } 
     } 
    }] 
) 

，如果你不数组中介意stamp_dt可以简化查询

db.collection.aggregate(
    [{ 
     $group: { 
      _id: "$stamp_dt", 
      "data": { 
       $push: "$$ROOT" 
      } 
     } 
    }] 
)