Question

我有一个收集＆＃34; MessageCenter＆＃34;我在哪里存储短信。

> db.MessageCenter.find().pretty()
{
        "_id" : ObjectId("567edae40b38770a1c847ccc"),
        "status" : 1,
        "from" : "567edace0b38770a1c847ccb",
        "name" : "abhishek rana",
        "creationtime" : 1451154148.937,
        "to" : "567ed86e0b387705ac92dcb2",
        "message" : "hello clone......."
}
{
        "_id" : ObjectId("567edb560b3877045c783f7a"),
        "status" : 1,
        "from" : "567edace0b38770a1c847ccb",
        "name" : "abhishek rana",
        "creationtime" : 1451154262.39,
        "to" : "567ed86e0b387705ac92dcb2",
        "message" : "hello clonee........................"
}
{
        "_id" : ObjectId("567edb770b38770b30d51477"),
        "status" : 0,
        "from" : "567edace0b38770a1c847ccb",
        "name" : "abhishek rana",
        "creationtime" : 1451154295.595,
        "to" : "567ed86e0b387705ac92dcb2",
        "message" : "hello clonee........................"
}

现在我想知道是否有一种方法可以将对象输出返回为：

{

            "from" : "567edace0b38770a1c847ccb",
            "to" : "567ed86e0b387705ac92dcb2",
            "name" : "abhishek rana",
            "message" : [
                             { 
                               "text" : "hello clone",
                               "creationtime" : 1451154148.937,
                               "status" : 1
                             }, 
                             { 
                               "text" : "another text",
                               "creationtime" : 1451154148.937,
                               "status" : 1
                             }
                        ]
}

因为我发现在一个数组中显示来自特定用户的所有消息而不是显示为多个对象更好。我希望如果有解决办法。感谢。

Answer 1

使用.aggregate()方法，$group和$project运算符。

db.MessageCenter.aggregate([
    { '$group': { 
        '_id': { 
            'from': '$from', 
            'to': '$to', 
            'name': '$name'
        }, 
        'message': { 
            '$push': { 
                'text': '$message',
                'creationtime': '$creationtime', 
                'status': '$status' 
            }
        }
    }},
    { '$project': { 
        'from': '$_id.from', 
        'to': '$_id.to', 
        'name': '$_id.name', 
        'message': 1, '_id': 0 
    } }
])

产生

{
        "message" : [
                {
                        "text" : "hello clone.......",
                        "creationtime" : 1451154148.937,
                        "status" : 1
                },
                {
                        "text" : "hello clonee........................",
                        "creationtime" : 1451154262.39,
                        "status" : 1
                },
                {
                        "text" : "hello clonee........................",
                        "creationtime" : 1451154295.595,
                        "status" : 0
                }
        ],
        "from" : "567edace0b38770a1c847ccb",
        "to" : "567ed86e0b387705ac92dcb2",
        "name" : "abhishek rana"
}

由mongodb中的类似字段组成

1 个答案: