mongodb $unwind 用于非理想嵌套文档

问题描述

我知道下面的 mongodb 文档可能不是一个理想的结构，但是有什么方法可以解开 $rounds.round_values?

I'm aware that the below mongodb document may not be in an ideal structure, but is there any way to unwind that $rounds.round_values?

我试过 aggregate([{"$unwind": "$rounds"}]) 或 "$rounds.round_values" 但是这似乎不起作用.非常感谢任何建议.

I've tried with aggregate([{"$unwind": "$rounds"}]), or "$rounds.round_values" but that doesn't seem to work. Any suggestions are greatly appreciated.

{
    "_id" : ObjectId("60bea750c26a1c7095387d00"),
    "rounds" : [
        {
            "round_number" : "0",
            "round_values" : {
                "max_player_pot" : "0.25",
                "pot_multiple" : "0.625",

        },
        {
            "round_number" : "1",
            "round_values" : {
                "max_player_pot" : "0.0",
                "pot_multiple" : "0.0",
        }
    ],
    "GameID" : "392124717",
    "ComputerName" : "awdfadf",

}

预期输出:

{
    "max_player_pot" : "0.25",
    "pot_multiple" : "0.625",
    "GameID" : "392124717",
    "ComputerName" : "awdfadf",
},
{
    "max_player_pot" : "0.0",
    "pot_multiple" : "0.0",
    "GameID" : "392124717",
    "ComputerName" : "awdfadf",
}

推荐答案

• $unwind 解构rounds数组
• $project 显示必填字段
• $unwind deconstruct the rounds array
• $project to show required fields

db.collection.aggregate([
  { $unwind: "$rounds" },
  {
    $project: {
      GameID: 1,
      ComputerName: 1,
      max_player_pot: "$rounds.round_values.max_player_pot",
      pot_multiple: "$rounds.round_values.pot_multiple"
    }
  }
])

游乐场

更动态的方法，

• $mergeObjects 合并根和 round_values 对象中的必填字段
• $replaceRoot 将上面的合并对象替换为根
• $mergeObjects to merge required fields from root and round_values object
• $replaceRoot to replace above merged object to root

db.collection.aggregate([
  { $unwind: "$rounds" },
  {
    $replaceRoot: {
      newRoot: {
        $mergeObjects: [
          {
            GameID: "$GameID",
            ComputerName: "$ComputerName"
          },
          "$rounds.round_values"
        ]
      }
    }
  }
])

游乐场

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