mongodb 聚合管道中的嵌套组

Question

我正在使用 Mongo 数据库，我有一个对象列表，我需要在类别 -> 子类别 -> 不同类型的子类别中分组。您可以在这个 mongodb playground > https://mongoplayground.net/p/BfR7FT28XKN

中找到代码

我创建组类别->所有子类别。但是如何将同名的子类别分组？

我的目标是实现这样的目标：

{
    "_id": "Food and Drink",
    "subCategories": [
      {
        "details": "Wine Bar",
        "subCategory": "Bar",
      },
      {
        "details": "Jazz and Blues Cafe",
        "subCategory": "Nightlife",
      },
      {
        "subCategory": "Restaurants",
        "types": [
              {
                "details": "Mediterranean",
                "subCategory": "Restaurants",
              },
              {
                "details": "Mexican",
                "subCategory": "Restaurants",
              }
           ]
       },
      
    ]
  }

谢谢

Answer 1

这是您需要的。您需要先按类别和子类别进行分组。我已经按类型推送了完整的文档。您可以过滤字段或根据您的要求进行更改。

[{
"$match": {
  "category": {
    "$ne": null
  },
  "subCategory": {
    "$ne": null
  }
 }
},
{
 $group: {
  _id: {
    cat: "$category",
    sub: "$subCategory",
    
   },
   docs: {
    $push: "$$ROOT"
   }
 }
},
{
$group: {
  _id: "$_id.cat",
  subCategories: {
    $push: {
      subCategory: "$_id.sub",
      types: "$docs"
    }
  }
 }
}]

从最后阶段删除 types: "$docs"，这就是您得到的

[{
"_id": "Community",
"subCategories": [
  {
    "subCategory": "Education"
  },
  {
    "subCategory": "Disabled Persons Services"
  }
 ]
},
{
 "_id": "Food and Drink",
 "subCategories": [
  {
    "subCategory": "Bar"
  },
  {
    "subCategory": "Nightlife"
  },
  {
    "subCategory": "Restaurants"
  }
 ]
}]

游乐场 https://mongoplayground.net/p/nwyAivJOZj5

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