我有一个架构,它有一个子数组,它的每个元素都引用另一个架构,如下所示:
{
_id: "5fed222d806311ec81d6df23"
someOtherNestedDoc: {
_id: "abc",
someOtherField: 10
},
matches: [
{
_id: "5fed222d806311ec81d6daf3",
user: "5fed222d806311ec81d6dcf3",
probability: 10
},
{
_id: "5fed222d806311ec81d6d1f3",
user: "5fed222d806311ec81d62cf3",
probability: 20
},
]
}
我想做一个 Mongoose 聚合,在其中我查找每个匹配项的用户引用,并且只为它投影 3 个字段,2 个已经存在,第三个是该模式数组的总和,以便最后,我有这样的事情:
{
_id: "5fed222d806311ec81d6df23"
someOtherNestedDoc: {
_id: "abc",
someOtherField: 10
},
matches: [
{
_id: "5fed222d806311ec81d6daf3",
user: {
firstName: "Max",
lastName: "Mustermann",
totalExpenses: 100
},
probability: 10
},
{
_id: "5fed222d806311ec81d6d1f3",
user: {
firstName: "Herbert",
lastName: "Mustermann",
totalExpenses: 200
},,
probability: 20
},
]
}
用户看起来像这样:
{
_id: "5fed222d806311ec81d6dcf3",
firstName: "Max",
lastName: "Mustermann",
password: "test",
expenses: [
{
_id: 1,
price: 50
},
{
_id: 2,
price: 50
},
]
}
{
_id: "5fed222d806311ec81d62cf3",
firstName: "Herbert",
lastName: "Mustermann",
password: "test2",
expenses: [
{
_id: 3,
price: 75
},
{
_id: 4,
price: 125
},
]
}
答案 0 :(得分:1)
$unwind
解构 matches
数组$lookup
带有用户集合并在 let 中传递用户 ID,
$match
userId 条件$project
显示必填字段,获取 expenses.price
的总和$unwind
解构 user
数组$group
by _id
并重建 matches
数组db.col1.aggregate([
{ $unwind: "$matches" },
{
"$lookup": {
"from": "user",
let: { userId: "$matches.user" },
pipeline: [
{ $match: { $expr: { $eq: ["$_id", "$$userId"] } } },
{
$project: {
_id: 0,
firstName: 1,
lastName: 1,
totalExpenses: { $sum: "$expenses.price" }
}
}
],
"as": "matches.user"
}
},
{ $unwind: "$matches.user" },
{
$group: {
_id: "$_id",
matches: { $push: "$matches" }
}
}
])