我们可以只比较MongoDB中的时间吗？

Question

我已经以日期时间格式存储了happyHours 酒店。现在我想获取所有happyHours 大于当前时间的酒店。

据我所知，我知道有日期比较来获取结果，但这会比较整个日期时间对象。

有没有办法只比较时间？

db 中的欢乐时光日期对象示例：

"happyHours" : {
    "mon" : [ 
        {
            "startTime" : ISODate("2016-04-11T06:30:59.000Z"),
            "endTime" : ISODate("2016-04-11T14:30:59.000Z")
        }
    ],
    "tue" : [ 
        {
            "startTime" : ISODate("2016-04-11T06:30:59.000Z"),
            "endTime" : ISODate("2016-04-11T14:30:59.000Z")
        }
    ],
    "wed" : [ 
        {
            "startTime" : ISODate("2016-04-11T06:30:59.000Z"),
            "endTime" : ISODate("2016-04-11T14:30:59.000Z")
        }
    ],
    "thu" : [ 
        {
            "startTime" : ISODate("2016-04-11T06:30:59.000Z"),
            "endTime" : ISODate("2016-04-11T14:30:59.000Z")
        }
    ],
    "fri" : [ 
        {
            "startTime" : ISODate("2016-04-11T06:30:59.000Z"),
            "endTime" : ISODate("2016-04-11T14:30:59.000Z")
        }
    ],
    "sat" : [ 
        {
            "startTime" : ISODate("2016-04-11T06:30:59.000Z"),
            "endTime" : ISODate("2016-04-11T14:30:59.000Z")
        }
    ],
    "sun" : [ 
        {
            "startTime" : ISODate("2016-04-11T06:30:59.000Z"),
            "endTime" : ISODate("2016-04-11T14:30:59.000Z")
        }
    ]
}

Answer 1

首先，当前模式不利于查询；在这种情况下，数组实际上是不必要的，如果您要将工作日作为键，那么更好的方法是丢失数组并仅引用元素：

"happyHours": {
    "mon": {
        "startTime" : ISODate("2016-04-11T06:30:59.000Z"),
        "endTime" : ISODate("2016-04-11T14:30:59.000Z")
    },
    ...
    "sun": {
        "startTime" : ISODate("2016-04-11T06:30:59.000Z"),
        "endTime" : ISODate("2016-04-11T14:30:59.000Z")
    }    
}

---

但是，一个更好的设计使查询更容易招手。您可以将happyHours 字段转换为一个数组，该数组包含一个文档，该文档分别描述了工作日、开始时间、开始分钟、结束小时和分钟，如下所示：

"happyHours": [
    {
        "weekDay": "mon",
        "startHour": 6,
        "startMinutes": 30,
        "endHour": 14
        "endMinutes": 30
    }
    ...
]

那么查询如下：

var now = new Date(),
    days = ['sun', 'mon', 'tue', 'wed', 'thu', 'fri', 'sun'],
    weekDay = days[now.getDay()],
    hour = now.getHours(),
    minutes = now.getMinutes();

db.hotels.find({
    "happyHours.weekDay": weekDay,
    "happyHours.startHour": { "$lte": hour },
    "happyHours.startMinutes": { "$lte": minutes },
    "happyHours.endHour": { "$gte": hour },
    "happyHours.endMinutes": { "$gte": minutes }
})

---

现在，如果您没有能力修改架构以符合上述建议，那么聚合框架提供了一种解决方法。考虑以下聚合管道，它在 $project 步骤中使用 date aggregation operators 并在随后的 $match 管道中查询：

 var now = new Date(),
    days = ['Sun', 'Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sun'],
    weekDay = days[now.getDay()],
    hour = now.getHours(),
    minutes = now.getMinutes();
    project = {
    "$project": {
        "otherfields": 1,
        "happyHours": 1,
        "happyHoursMonStartHour": { "$hour": "$happyHours.mon.startTime" },
        "happyHoursMonStartMinutes": { "$minute": "$happyHours.mon.startTime" },
        "happyHoursMonEndHour": { "$hour": "$happyHours.mon.endTime" },
        "happyHoursMonEndMinutes": { "$minute": "$happyHours.mon.endTime" },
        "happyHoursTueStartHour": { "$hour": "$happyHours.tue.startTime" },
        "happyHoursTueStartMinutes": { "$minute": "$happyHours.tue.startTime" },
        "happyHoursTueEndHour": { "$hour": "$happyHours.tue.endTime" },
        "happyHoursTueEndMinutes": { "$minute": "$happyHours.tue.endTime" },
        "happyHoursWedStartHour": { "$hour": "$happyHours.wed.startTime" },
        "happyHoursWedStartMinutes": { "$minute": "$happyHours.wed.startTime" },
        "happyHoursWedEndHour": { "$hour": "$happyHours.wed.endTime" },
        "happyHoursWedEndMinutes": { "$minute": "$happyHours.wed.endTime" },
        "happyHoursThuStartHour": { "$hour": "$happyHours.thu.startTime" },
        "happyHoursThuStartMinutes": { "$minute": "$happyHours.thur.startTime" },
        "happyHoursThuEndHour": { "$hour": "$happyHours.thu.endTime" },
        "happyHoursThuEndMinutes": { "$minute": "$happyHours.thu.endTime" },
        "happyHoursFriStartHour": { "$hour": "$happyHours.fri.startTime" },
        "happyHoursFriStartMinutes": { "$minute": "$happyHours.fri.startTime" },
        "happyHoursFriEndHour": { "$hour": "$happyHours.fri.endTime" },
        "happyHoursFriEndMinutes": { "$minute": "$happyHours.fri.endTime" },
        "happyHoursSatStartHour": { "$hour": "$happyHours.sat.startTime" },
        "happyHoursSatStartMinutes": { "$minute": "$happyHours.sat.startTime" },
        "happyHoursSatEndHour": { "$hour": "$happyHours.sat.endTime" },
        "happyHoursSatEndMinutes": { "$minute": "$happyHours.sat.endTime" },
        "happyHoursSunStartHour": { "$hour": "$happyHours.sun.startTime" },
        "happyHoursSunStartMinutes": { "$minute": "$happyHours.sun.startTime" },
        "happyHoursSunEndHour": { "$hour": "$happyHours.sun.endTime" },
        "happyHoursSunEndMinutes": { "$minute": "$happyHours.sun.endTime" },
    }
    },
    match = { "$match": {} },    
    pipeline = [
    { "$unwind": "$happyHours.mon" },
    { "$unwind": "$happyHours.tue" },
    { "$unwind": "$happyHours.wed" },
    { "$unwind": "$happyHours.thur" },
    { "$unwind": "$happyHours.fri" },
    { "$unwind": "$happyHours.sat" },
    { "$unwind": "$happyHours.sun" }    
    ];

match["$match"]["happyHours"+ weekDay +"StartHour"] = { "$lte": hour };
match["$match"]["happyHours"+ weekDay +"StartMinutes"] = { "$lte": minutes };
match["$match"]["happyHours"+ weekDay +"EndHour"] = { "$gte": minutes };
match["$match"]["happyHours"+ weekDay +"EndMinutes"] = { "$gte": minutes };
pipeline.push(project);
pipeline.push(match);

db.hotels.aggregate(pipeline);

---

在使用printjson(pipeline) 运行管道之前打印管道会显示：

[
    {
        "$unwind" : "$happyHours.mon"
    },
    {
        "$unwind" : "$happyHours.tue"
    },
    {
        "$unwind" : "$happyHours.wed"
    },
    {
        "$unwind" : "$happyHours.thur"
    },
    {
        "$unwind" : "$happyHours.fri"
    },
    {
        "$unwind" : "$happyHours.sat"
    },
    {
        "$unwind" : "$happyHours.sun"
    },
    {
        "$project" : {
            "otherfields" : 1,
            "happyHours" : 1,
            "happyHoursMonStartHour" : {
                "$hour" : "$happyHours.mon.startTime"
            },
            "happyHoursMonStartMinutes" : {
                "$minute" : "$happyHours.mon.startTime"
            },
            "happyHoursMonEndHour" : {
                "$hour" : "$happyHours.mon.endTime"
            },
            "happyHoursMonEndMinutes" : {
                "$minute" : "$happyHours.mon.endTime"
            },
            "happyHoursTueStartHour" : {
                "$hour" : "$happyHours.tue.startTime"
            },
            "happyHoursTueStartMinutes" : {
                "$minute" : "$happyHours.tue.startTime"
            },
            "happyHoursTueEndHour" : {
                "$hour" : "$happyHours.tue.endTime"
            },
            "happyHoursTueEndMinutes" : {
                "$minute" : "$happyHours.tue.endTime"
            },
            "happyHoursWedStartHour" : {
                "$hour" : "$happyHours.wed.startTime"
            },
            "happyHoursWedStartMinutes" : {
                "$minute" : "$happyHours.wed.startTime"
            },
            "happyHoursWedEndHour" : {
                "$hour" : "$happyHours.wed.endTime"
            },
            "happyHoursWedEndMinutes" : {
                "$minute" : "$happyHours.wed.endTime"
            },
            "happyHoursThuStartHour" : {
                "$hour" : "$happyHours.thu.startTime"
            },
            "happyHoursThuStartMinutes" : {
                "$minute" : "$happyHours.thur.startTime"
            },
            "happyHoursThuEndHour" : {
                "$hour" : "$happyHours.thu.endTime"
            },
            "happyHoursThuEndMinutes" : {
                "$minute" : "$happyHours.thu.endTime"
            },
            "happyHoursFriStartHour" : {
                "$hour" : "$happyHours.fri.startTime"
            },
            "happyHoursFriStartMinutes" : {
                "$minute" : "$happyHours.fri.startTime"
            },
            "happyHoursFriEndHour" : {
                "$hour" : "$happyHours.fri.endTime"
            },
            "happyHoursFriEndMinutes" : {
                "$minute" : "$happyHours.fri.endTime"
            },
            "happyHoursSatStartHour" : {
                "$hour" : "$happyHours.sat.startTime"
            },
            "happyHoursSatStartMinutes" : {
                "$minute" : "$happyHours.sat.startTime"
            },
            "happyHoursSatEndHour" : {
                "$hour" : "$happyHours.sat.endTime"
            },
            "happyHoursSatEndMinutes" : {
                "$minute" : "$happyHours.sat.endTime"
            },
            "happyHoursSunStartHour" : {
                "$hour" : "$happyHours.sun.startTime"
            },
            "happyHoursSunStartMinutes" : {
                "$minute" : "$happyHours.sun.startTime"
            },
            "happyHoursSunEndHour" : {
                "$hour" : "$happyHours.sun.endTime"
            },
            "happyHoursSunEndMinutes" : {
                "$minute" : "$happyHours.sun.endTime"
            }
        }
    },
    {
        "$match" : {
            "happyHoursThuStartHour" : {
                "$lte" : 9
            },
            "happyHoursThuStartMinutes" : {
                "$lte" : 34
            },
            "happyHoursThuEndHour" : {
                "$gte" : 34
            },
            "happyHoursThuEndMinutes" : {
                "$gte" : 34
            }
        }
    }
]