在mongodb中按月份和日期分组并显示列表

Posted 2023-03-11

【中文标题】在mongodb中按月份和日期分组并显示列表

【英文标题】：Group by month and date in mongodb and display the list

【发布时间】：2021-09-21 13:50:31

【问题描述】：

我的数据库产品架构结构

 "_id" :  "507d95d5719dbef170f15bf9" , "name" : "AC3 Series Charger", "type" : "accessory", "price" : 19,"created":"1626083461034"
 "_id" :  "507d95d5719dbef170f15bfa" , "name" : "AC3 Case Green", "type" : "case" ,  "price" : 12, "created":"1625805979235"
 "_id" :  "507d95d5719dbef170f15bfb" , "name" : "Phone Extended Warranty", "type" : "warranty", "price" : 38,"created":"1624374320653" 
 "_id" :  "507d95d5719dbef170f15bfc" , "name" : "AC3 Case Black", "type" :  "case" , "price" : 12.5,"created":"1624606153646" 
 "_id" :  "507d95d5719dbef170f15bfd" , "name" : "AC3 Case Red", "type" : "case" , "price" : 12, "created":"1624362066717"
 "_id" :  "507d95d5719dbef170f15bfe" , "name" : "Phone Service Basic Plan", "type" : "service", "price":9.5,"created":"1624446320186"
 "_id" :  "507d95d5719dbef170f15bff" , "name" : "Phone Service Core Plan", "type" : "service", "price" :3.5,"created":"1624605403064"
 "_id" :  "507d95d5719dbef170f15c00" , "name" : "Phone Service Family Plan", "type" : "service", "price":10.4,"created":"1624446320173"

我想获取基于 month and day 的记录，为此，我编写了如下查询

db.collection.aggregate([
     "$group": 
            _id:  month: "$month":  "$toDate": "$created" , day: "$day"   ,
            product:  "$push": "$name" 
    
  ])

但它给出了错误

An object representing an expression must have exactly one field:  $month:  $toDate: \"$created\" , day: \"$day\" 

预期输出

 
      month:5
      day:12
      products:[
          
            "name" : "Phone Service Family Plan"
          ,
          "name" : "Phone Service Core Plan"
      ]
  

【问题讨论】：

"$day" - 您在示例文档中没有该字段。我认为您还可以使用适当的聚合运算符将created 字段转换为day（我认为有一个$day 聚合运算符）。

【参考方案1】：

您需要先使用 $toLong 将字符串转换为 long 并使用 $dayOfMonth 运算符，因为 MongoDB 中没有 $day：

db.collection.aggregate([
    
        "$group": 
            _id: 
                month:  "$month":  "$toDate":  $toLong: "$created"   ,
                day:  "$dayOfMonth":  "$toDate":  $toLong: "$created"   
                
            ,
            product: 
                "$push": "$name"
                
            
    ,
    
        $group: 
            _id: "$_id.month",
            monthDays: 
                $push: 
                    day: "$_id.day",
                    product: "$product"
                
            
        
    ,
    
        $project: 
            _id: 0,
            month: "$_id",
            monthDays: 1
        
    ,
])

Mongo Playground

【讨论】：

月份数据正在分组。查看第 7 个月的结果

@ram12393 我不完全明白出了什么问题，你能粘贴给定数据的预期结果吗？

此解决方案按（月和日）对（我相信）您所期望的进行分组

如果您查看查询结果，有 7 个月的记录是不同日期的倍数。我的问题是我们如何在单个数组下根据天而不是倍数来做同月记录。

你收到我的问题了吗？？