Mongodb 用于嵌套文档生成的Mongo DB聚合管道帮助

在mongodb聚合和管道概念中尝试了许多方法，但未能完全实现我的项目所需的以下格式

我在Mongodb集合中的数据格式如下

[{
    "title" : "Product Title 1",
    "desc" : "Product Description 1",
    "year" : 2019,
    "productkey" : "A"
},
{
    "title" : "Product Title 2",
    "desc" : "Product Description 2",
    "year" : 2019,
    "productkey" : "A"
},,
{
    "title" : "Product Title 3",
    "desc" : "Product Description 3",
    "year" : 2018,
    "productkey" : "A"
},
{
    "title" : "Product Title 4",
    "desc" : "Product Description 4",
    "year" : 2018,
    "productkey" : "A"
},
[{
    "title" : "Product Title 5",
    "desc" : "Product Description 5",
    "year" : 2019,
    "productkey" : "B"
},
{
    "title" : "Product Title 6",
    "desc" : "Product Description 6",
    "year" : 2019,
    "productkey" : "B"
},
{
    "title" : "Product Title 7",
    "desc" : "Product Description 7",
    "year" : 2018,
    "productkey" : "B"
},
{
    "title" : "Product Title 8",
    "desc" : "Product Description 8",
    "year" : 2018,
    "productkey" : "B"
},
{
    "title" : "Product Title 9",
    "desc" : "Product Description 9",
    "year" : 2019,
    "productkey" : "C"
},
{
    "title" : "Product Title 10",
    "desc" : "Product Description 10",
    "year" : 2019,
    "productkey" : "C"
},
{
    "title" : "Product Title 11",
    "desc" : "Product Description 11",
    "year" : 2018,
    "productkey" : "C"
}] 

我正在尝试使用聚合和管道实现以下格式

[{
    "productkey" : "A",
    "details":
    [
        {
            "year": 2019,
            "subdetails":[
                {
                    "title" : "Product Title 1",
                    "desc" : "Product Description 1",
                },
                {
                    "title" : "Product Title 2",
                    "desc" : "Product Description 2",
                }           
            ]
        },
        {
            "year": 2018,
            "subdetails":[
                {
                    "title" : "Product Title 3", "desc" : "Product Description 3",
                },
                {
                    "title" : "Product Title 4",
                    "desc" : "Product Description 4",
                }           
            ]

        } 
    ]
},
{
    "productkey" : "B",
    "details":
    [
        {
            "year": 2019,
            "subdetails":[
                {
                    "title" : "Product Title 5",
                    "desc" : "Product Description 5",
                },
                {
                    "title" : "Product Title 6",
                    "desc" : "Product Description 6",
                }           
            ]
        },
        {
            "year": 2018,
            "subdetails":[
                {
                    "title" : "Product Title 7",
                    "desc" : "Product Description 7",
                },
                {
                    "title" : "Product Title 8",
                    "desc" : "Product Description 8",
                }           
            ]

        } 
    ]
},
{
    "productkey" : "C",
    "details":
    [
        {
            "year": 2019,
            "subdetails":[
                {
                    "title" : "Product Title 9",
                    "desc" : "Product Description 9",
                },
                {
                    "title" : "Product Title 10",
                    "desc" : "Product Description 10",
                }           
            ]
        },
        {
            "year": 2018,
            "subdetails":[
                {
                    "title" : "Product Title 11",
                    "desc" : "Product Description 11",
                }       
            ]

        } 
    ]
}]

---

那么我如何才能做到这一点呢？

您可以使用下面的聚合

db.collection.aggregate([
  { "$group": {
    "_id": { "productkey": "$productkey", "year": "$year" },
    "subDetails": { "$push": { "title": "$title", "desc": "$desc" }}
  }},
  { "$group": {
    "_id": "$_id.productkey",
    "details": { "$push": { "year": "$_id.year", "subDetails": "$subDetails" }}
  }}
])

---

在上述解决方案中，是否可以在详细信息级别按年份进行排序？在

$group

{$sort:{“details.year”：1}}两个组之间添加一个

$sort

阶段，尝试在组之间添加，但运气不佳

{$sort:{“\id.year”：1}