多个文档之间的MongoDB dateDiff

问题描述

我的mongoDB中有一个集合，其中存储了提供给客户的服务以及他们的电子邮件地址，如下所示:

I have collection in my mongoDB which stores service given to customer along with their email address something like below

{
    "_id" : ObjectId("56a84627f8fd4a136c0e944a"),    
    "Vehicle" : "Honda",
    "ServiceSelected" : "FULL SERVICE",
    "FullName" : "xyz",
    "Email" : "[email protected]",    
    "BookingTime" : ISODate("2015-12-27T06:00:00.000Z")
},

{
    "_id" : ObjectId("56a84627f8fd4a136c0e944b"),    
    "Vehicle" : "AUDI",
    "ServiceSelected" : "FLAT TYRE",
    "FullName" : "abc",
    "Email" : "[email protected]",    
    "BookingTime" : ISODate("2015-12-26T06:00:00.000Z")
},

{
    "_id" : ObjectId("56a84627f8fd4a136c0e944c"),    
    "Vehicle" : "BMW",
    "ServiceSelected" : "OTHERS",
    "FullName" : "def",
    "Email" : "[email protected]",    
    "BookingTime" : ISODate("2015-12-25T06:00:00.000Z")
},

{
    "_id" : ObjectId("56a84627f8fd4a136c0e944d"),    
    "Vehicle" : "BMW",
    "ServiceSelected" : "OTHERS",
    "FullName" : "def",
    "Email" : "[email protected]",    
    "BookingTime" : ISODate("2015-12-30T06:00:00.000Z")
},

{
    "_id" : ObjectId("56a84627f8fd4a136c0e944a"),    
    "Vehicle" : "Honda",
    "ServiceSelected" : "FULL SERVICE",
    "FullName" : "xyz",
    "Email" : "[email protected]",    
    "BookingTime" : ISODate("2016-01-27T06:00:00.000Z")
}

我要从上述集合中获取所有已使用我们服务的文档，至少要间隔30天，即应从以上集合电子邮件"中返回:"[email protected]"，但不应返回电子邮件":"[email protected]"，因为第二个服务是在5天内获得的.

From the above collection I want to fetch all the documents that have taken our service with a gap of at-least 30 days i.e. from the above collection "Email" : "[email protected]" should be returned but not "Email" : "[email protected]" as the second service was taken with in 5 days.

我知道设计存在缺陷，可以在从应用程序插入记录时设置其他标志，但是我需要获取现有记录的数据.

I know there is flaw in the design and an additional flag can be set while inserting the record from the application but I need to fetch the data for the existing records.

推荐答案

您需要使用 $min 和 $max 运算符，它们分别在您的 $group 阶段.管道的最后一个阶段是 $redact 使用 $divide 和 $subtract 算术运算符.返回第一个服务"到最后一个服务"之间的天数大于30的那些文档.

You need to use the $min and $max operators which respectively return the minimum and maximum value for "BookingTime" in your $group stage. The last stage in the pipeline is the $redact stage where you use a simple "date" math using the $divide and $subtract arithmetic operators.to return those documents where the number of days between first "service" and last "service" is greater than 30

db.collection.aggregate( [ 
    { "$group": { 
        "_id": "$Email",  
        "date1": { "$min": "$BookingTime" }, 
        "date2": { "$max": "$BookingTime" } 
    }}, 
    { "$redact": { 
        "$cond": [ 
             { "$gte": [ 
                 { "$divide": [ 
                     { "$subtract": [ "$date2", "$date1" ] }, 
                     1000 * 60 * 60 * 24 
                 ]}, 
                 30 
             ]}, 
             "$$KEEP", 
             "$$PRUNE" 
        ] 
    }}
])

哪个返回:

{
        "_id" : "[email protected]",
        "date1" : ISODate("2015-12-27T06:00:00Z"),
        "date2" : ISODate("2016-01-27T06:00:00Z")
}

另一种方法是使用 $cond 运算符在$project阶段可避免进行集合扫描.

Another way to do this is by using the $cond operator in a $project stage to avoid a collection scan.

db.collection.aggregate( [ 
    { "$group": { 
        "_id": "$Email", 
        "date1": { "$min": "$BookingTime" },
        "date2": { "$max": "$BookingTime" }, 
        "count": { "$sum": 1 } 
    }},
    { "$match": { "count": { "$gte": 2 } } }, 
    { "$project": { 
        "emails": { 
            "$cond": [ 
                { "$gte": [ 
                    { "$divide": [ 
                        { "$subtract": [ "$date2", "$date1" ] }, 
                        1000 * 60 * 60 * 24 
                    ]}, 
                    30 
                ] }, 
                "$_id", 
                false 
            ] 
        } 
    }}, 
    { "$match": { "emails": { "$ne": false } } } 
])

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