计算年,月,日的日期差异

Question

我有以下查询:

db.getCollection('user').aggregate([
   {$unwind: "$education"},
   {$project: {
      duration: {"$divide":[{$subtract: ['$education.to', '$education.from'] }, 1000 * 60 * 60 * 24 * 365]}
   }},
   {$group: {
     _id: '$_id',
     "duration": {$sum: '$duration'}  
   }}]
])

以上查询结果为:

{
    "_id" : ObjectId("59fabb20d7905ef056f55ac1"),
    "duration" : 2.34794520547945
}

/* 2 */
{
    "_id" : ObjectId("59fab630203f02f035301fc3"),
    "duration" : 2.51232876712329
}

但我想要做的是以year+ month+ day格式获取其持续时间,例如:2 y, 3 m, 20 d.另外一点,如果一个球场上的to球场是空的,另一个球场isGoingOn: true,所以在这里我应该用当前日期而不是to场来计算持续时间.用户有一系列课程子文档

education: [
   {
      "courseName": "Java",
      "from" : ISODate("2010-12-08T00:00:00.000Z"),
      "to" : ISODate("2011-05-31T00:00:00.000Z"), 
      "isGoingOn": false
   },
   {
      "courseName": "PHP",
      "from" : ISODate("2013-12-08T00:00:00.000Z"),
      "to" : ISODate("2015-05-31T00:00:00.000Z"), 
      "isGoingOn": false
   },
   {
      "courseName": "Mysql",
      "from" : ISODate("2017-02-08T00:00:00.000Z"),
      "to" : null, 
      "isGoingOn": true
   }
]

另一点是:该日期在一个子文档中可能不连续到另一个子文档.用户可能有1年的课程,然后在两年后,他/她开始他/她的下一个课程1年和3个月(这意味着该用户总共有2年和3个月的课程持续时间) .我想要的是在educations数组中获取每个子文档的日期差异,并将它们相加.假设我的样本数据Java课程持续时间是6个月,22天,PHP课程持续时间是1年,6个月,22天,最后一个是从2017年2月8日到现在,并且它正在进行,所以我的教育持续时间是这些间隔的总和.

Answer 1

请尝试此聚合以获取以天、月和年为单位的日期差异，添加多$addFields阶段计算并减少日期差异，月份范围无下溢，此处假设为 1 个月 = 30 天

管道

db.edu.aggregate(
    [
        {
            $addFields : {
                trainingPeriod : {
                    $map : {
                        input : "$education",
                        as : "t",
                        in : {
                            year: {$subtract: [{$year : {$ifNull : ["$$t.to", new Date()]}}, {$year : "$$t.from"}]},
                            month: {$subtract: [{$month : {$ifNull : ["$$t.to", new Date()]}}, {$month : "$$t.from"}]},
                            dayOfMonth: {$subtract: [{$dayOfMonth : {$ifNull : ["$$t.to", new Date()]}}, {$dayOfMonth : "$$t.from"}]}
                        }
                    }
                }
            }
        },
        {
            $addFields : {
                trainingPeriod : {
                    $map : {
                        input : "$trainingPeriod",
                        as : "d",
                        in : {
                            year: "$$d.year",
                            month: {$cond : [{$lt : ["$$d.dayOfMonth", 0]}, {$subtract : ["$$d.month", 1]}, "$$d.month" ]},
                            day: {$cond : [{$lt : ["$$d.dayOfMonth", 0]}, {$add : [30, "$$d.dayOfMonth"]}, "$$d.dayOfMonth" ]}
                        }
                    }
                }
            }
        },
        {
            $addFields : {
                trainingPeriod : {
                    $map : {
                        input : "$trainingPeriod",
                        as : "d",
                        in : {
                            year: {$cond : [{$lt : ["$$d.month", 0]}, {$subtract : ["$$d.year", 1]}, "$$d.year" ]},
                            month: {$cond : [{$lt : ["$$d.month", 0]}, {$add : [12, "$$d.month"]}, "$$d.month" ]},
                            day: "$$d.day"
                        }
                    }
                }
            }
        },
        {
            $addFields : {
                total : {
                    $reduce : {
                        input : "$trainingPeriod",
                        initialValue : {year : 0, month : 0, day : 0},
                        in : {
                            year: {$add : ["$$this.year", "$$value.year"]},
                            month: {$add : ["$$this.month", "$$value.month"]},
                            day: {$add : ["$$this.day", "$$value.day"]}
                        }
                    }
                }
            }
        },
        {
            $addFields : {
                total : {
                    year : "$total.year",
                    month : {$add : ["$total.month", {$floor : {$divide : ["$total.day", 30]}}]},
                    day : {$mod : ["$total.day", 30]}
                }
            }
        },
        {
            $addFields : {
                total : {
                    year : {$add : ["$total.year", {$floor : {$divide : ["$total.month", 12]}}]},
                    month : {$mod : ["$total.month", 12]},
                    day : "$total.day"
                }
            }
        }
    ]
).pretty()

结果

{
    "_id" : ObjectId("5a895d4721cbd77dfe857f95"),
    "education" : [
        {
            "courseName" : "Java",
            "from" : ISODate("2010-12-08T00:00:00Z"),
            "to" : ISODate("2011-05-31T00:00:00Z"),
            "isGoingOn" : false
        },
        {
            "courseName" : "PHP",
            "from" : ISODate("2013-12-08T00:00:00Z"),
            "to" : ISODate("2015-05-31T00:00:00Z"),
            "isGoingOn" : false
        },
        {
            "courseName" : "Mysql",
            "from" : ISODate("2017-02-08T00:00:00Z"),
            "to" : null,
            "isGoingOn" : true
        }
    ],
    "trainingPeriod" : [
        {
            "year" : 0,
            "month" : 5,
            "day" : 23
        },
        {
            "year" : 1,
            "month" : 5,
            "day" : 23
        },
        {
            "year" : 1,
            "month" : 0,
            "day" : 10
        }
    ],
    "total" : {
        "year" : 2,
        "month" : 11,
        "day" : 26
    }
}
>