将字段更新为排序嵌套数组字段

Question

我有一个集合主题的文档，它具有以下嵌套数组

[
  {
    _id: ObjectId("618c6718c6a8cc3a84a0b37f"),
    subscribers: [ 
     {userId: ObjectId("618c643545f4ecd43e9b20f7"), points: {daily: 50, total: 100} }, 
     {userId: ObjectId("618c641345f4ecd43e9b20f0"), points: {daily: 10, total: 80} }, 
     {userId: ObjectId("618c648c45f4ecd43e9b20fc"), points: {daily: 20, total: 80} }
    ],
    quizzes: [],
    leaderboards: {
      daily: [],
      total: []
    },
  }
]

是否按每日点对订阅者列表进行排序，并将结果设置为领导板字段中嵌套的每日数组？

也就是说，我希望我的文档在查询后会像这样

[
  {
    _id: ObjectId("618c6718c6a8cc3a84a0b37f"),
    subscribers: [ 
     {userId: ObjectId("618c643545f4ecd43e9b20f7"), points: {daily: 20, total: 70} }, 
     {userId: ObjectId("618c641345f4ecd43e9b20f0"), points: {daily: 10, total: 60} }, 
     {userId: ObjectId("618c648c45f4ecd43e9b20fc"), points: {daily: 15, total: 50} }
    ],
    quizzes: [],
    leaderboards: {
      daily: [
       {userId: ObjectId("618c643545f4ecd43e9b20f7"), points: {daily: 20, total: 70} },
       {userId: ObjectId("618c648c45f4ecd43e9b20fc"), points: {daily: 15, total: 50} } 
       {userId: ObjectId("618c641345f4ecd43e9b20f0"), points: {daily: 10, total: 60} }, 
       
    ],
      total: []
    },
  }
]

我找到了以下代码

db.collection.aggregate(
{ $unwind: "$memberships" },
{ $sort: { "memberships.price": 1 }},
{ $group: {
    _id: "$_id",
    "memberships": { $push: "$memberships" }
  }
})

来自猫鼬排序嵌套的对象数组不能工作

此聚合可以工作，但它对订阅者进行排序，而不是使用结果数组更新每日嵌套字段。

Answer 1

你实际上是在正确的轨道上。您只需要使用$merge来更新回集合。

db.Topic.aggregate([
  {
    $unwind: "$subscribers"
  },
  {
    $sort: {
      "subscribers.points.daily": -1
    }
  },
  {
    $group: {
      _id: "$_id",
      "daily": {
        $push: "$subscribers"
      }
    }
  },
  {
    $project: {
      leaderboards: {
        daily: "$daily"
      }
    }
  },
  {
    "$merge": {
      "into": "Topic",
      "on": "_id",
      "whenMatched": "merge"
    }
  }
])

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Answer 2

@ray的答案是正确的，而且会工作得很好。

我将使用单个$set阶段重写查询，并使用$function操作符对嵌套字段进行排序。

db.collection.aggregate([
  {
    "$set": {
      "leaderboards.daily": {
        "$function": {
          "body": "function(arr) {return arr.sort((a,b) => (a.points.daily < b.points.daily) ? 1 : ((b.points.daily > a.points.daily) ? -1 : 0));}",
          "args": [
            "$subscribers"
          ],
          "lang": "js",
          
        },
        
      },
      
    }
  }
])

Mongo游乐场示例执行