mongodb $unwind 用于非理想嵌套文档

本文介绍了mongodb $unwind 用于非理想嵌套文档的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 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" } } ])

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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" ] } } } ])

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