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嵌套数组上的猫鼬聚合

aggregate mongoose mongodb javascript

phoebus · 技术社区 · 3 年前

我有一个模式,它有一个子数组,每个元素都引用另一个模式如下:

{
 _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的用户引用,并且只为它项目3个字段,其中2个已经存在,第三个是该模式的数组之和,所以最后,我有这样的结果:

{
 _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
    },
   ]
}

0 回复 | 直到 3 年前

turivishal 3 年前

$unwind 解构 matches 阵列
$lookup 在let中收集用户并传递用户id,
- $match userId条件
- $project 要显示必填字段,请获取以下值的总和 expenses.price
$放松 解构 user 阵列
$group 通过 _id 并重建 比赛 阵列

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" }
    }
  }
])

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