将 MongoDB 集合转换为嵌套对象数组

Posted 2023-02-26

【中文标题】将 MongoDB 集合转换为嵌套对象数组

【英文标题】：Convert MongoDB Collection to Array of Nested Object

【发布时间】：2021-07-07 07:12:40

【问题描述】：

我的mongo数据格式如下：

 country: "Bangladesh", city: "Dhaka", name: "Jobayer", email: "[e-mail]" 
 country: "Bangladesh", city: "Dhaka", name: "Mehotaz", email: "[e-mail]" 
 country: "KSA", city: "Dammam", name: "Jabal", email: "[e-mail]" 

我想检索如下数据：

[
    
        country: 'Bangladesh',
        cities: [
            
                city: 'Dhaka',
                contacts: [
                    
                        name: 'Jobayer',
                        email: '[e-mail]'
                    ,
                    
                        name: 'Mehotaz',
                        email: '[e-mail]'
                    
                ]
            
        ]
    ,
    
        country: 'KSA',
        cities: [
            
                city: 'Dammam',
                contacts: [
                    
                        name: 'Jabal',
                        email: '[e-mail]'
                    
                ]
            
        ]
    
];

我尝试了一些分组操作，但无法获得预期的结果。请就我如何实现这一目标提出宝贵的建议。

【参考方案1】：

你想做的是两次$group，一次是country x city，然后是国家，就像这样：

db.collection.aggregate([
  
    $group: 
      _id: 
        country: "$country",
        city: "$city"
      ,
      contacts: 
        $push: 
          name: "$name",
          email: "$email"
        
      
    
  ,
  
    $group: 
      _id: "$_id.country",
      cities: 
        $push: 
          city: "$_id.city",
          contacts: "$contacts"
        
      
    
  
])

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