MongoDB -如何使用深嵌套数组进行聚合
MongoDB -如何使用深嵌套数组进行聚合
提问于 2022-03-30 10:19:47
我有以下MongoDB结构：
部门集合：
{
"_id": ObjectId("5b28cab902f28e18b863bd36"),
"name": "Premier League",
...
"teams": [
ObjectId("5b28cab902f28e18b863bd01"),
ObjectId("5b28cab902f28e18b863bd02"),
ObjectId("5b28cab902f28e18b863bd03"),
...
]
...
},
...团队集合：
{
"_id": ObjectId("5b28cab902f28e18b863bd01"),
"name": "Liverpool",
...
"players": [
ObjectId('5b23tmb902f28e18b863bd01'),
ObjectId('5b23tmb902f28e18b863bd02'),
ObjectId('5b23tmb902f28e18b863bd03'),
...
]
...
},
...播放机收藏：
{
"_id": ObjectId("5b2b9a8bbda339352cc39ec1"),
"name": "Mohamed Salah",
"nationality": [
ObjectId("5b23cn1902f28e18b863bd01"),
ObjectId("5b23cn2902f28e18b863bd02"),
],
...
},
...Countries 藏品：
{
"_id": ObjectId("5b23cn1902f28e18b863bd01"),
"name": "England",
...
},
{
"_id": ObjectId("5b23cn2902f28e18b863bd02"),
"name": "Egypt",
...
},
...如何使用MongoDB聚合($lookup、$pipeline等)获得结果，如下所示：
{
"divisions": [
{
"_id": ObjectId("5b28cab902f28e18b863bd36"),
"name": "Premier League",
...
"teams": [
{
"_id": ObjectId("5b28cab902f28e18b863bd01"),
"name": "Liverpool",
...
"players": [
{
"_id": ObjectId("5b23tmb902f28e18b863bd01"),
"name": "Mohamed Salah",
"nationality": [
{
"_id": ObjectId("5b23cn2902f28e18b863bd02"),
"name": "Egypt",
...
},
{
"_id": ObjectId("5b23cn1902f28e18b863bd01"),
"name": "England",
...
}
]
...
},
...
]
},
...
]
},
{
"_id": ObjectId("5b28cab902f28e18b863bd37"),
"name": "Championship",
...
},
...
]
}我设法进行了一级合并：
db.divisions.aggregate([
{
$lookup: {
from: 'teams',
localField: 'teams',
foreignField: '_id',
as: 'teams'
}
},
])然后我遇到了困难，所以如果有人能帮我解决这个问题，我将非常感激。
回答 2
Stack Overflow用户
回答已采纳
发布于 2022-03-30 12:22:43
您需要多层嵌套$lookup和pipeline。
db.division.aggregate([
{
$lookup: {
from: "teams",
let: {
teams: "$teams"
},
pipeline: [
{
$match: {
$expr: {
$in: [
"$_id",
"$$teams"
]
}
}
},
{
$lookup: {
from: "players",
let: {
players: "$players"
},
pipeline: [
{
$match: {
$expr: {
$in: [
"$_id",
"$$players"
]
}
}
},
{
$lookup: {
from: "countries",
localField: "nationality",
foreignField: "_id",
as: "nationality"
}
}
],
as: "players"
}
}
],
as: "teams"
}
}
])Stack Overflow用户
发布于 2022-03-30 23:42:31
也许有人会有用。还可以使用populate方法合并数据：
db.divisions.find(_id: division_id).populate(
{
path: 'teams',
populate: {
path: 'players',
populate: {
path: 'nationality'
}
}
}
)页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/71675424
复制相关文章
相似问题
腾讯云开发者
