如何避免 mongodb 文档中的对象数组重复答案

【问题标题】：How to avoid duplication in array of objects in a mongodb document如何避免 mongodb 文档中的对象数组重复
【发布时间】：2021-12-19 05:16:07
【问题描述】：

这是文档示例：

{
    "_id": "658016",
    "playerName": "Kuldeep Singh",
    "tournamentId": "197831",
    "score": [
        {
            "_id": "1611380",
            "runsScored": 21,
            "ballFaced": 10,
            "fours": 3,
            "sixes": 1,
            "strikeRate": 210,
            "oversBowled": 3,
            "runsConceded": 34,
            "economyRate": 11.33,
            "wickets": 0,
            "maiden": 0,
            "howToOut": "c Mayank b Nitin Gudle -(reddy)",
            "catches": [],
            "stumping": [],
            "runout": [],
            "participatedRunout": []
        },
        {
            "_id": "1602721",
            "runsScored": 21,
            "ballFaced": 14,
            "fours": 1,
            "sixes": 1,
            "strikeRate": 150,
            "oversBowled": 3,
            "runsConceded": 28,
            "economyRate": 9.33,
            "wickets": 0,
            "maiden": 0,
            "howToOut": "not out",
            "catches": [],
            "stumping": [],
            "runout": [],
            "participatedRunout": []
        },
        {
            "_id": "1536540",
            "runsScored": 1,
            "ballFaced": 3,
            "fours": 0,
            "sixes": 0,
            "strikeRate": 33.33,
            "oversBowled": 2,
            "runsConceded": 7,
            "economyRate": 3.5,
            "wickets": 3,
            "maiden": 0,
            "howToOut": "b Lalit",
            "catches": [],
            "stumping": [],
            "runout": [],
            "participatedRunout": []
        },
        {
            "_id": "1536483",
            "runsScored": 0,
            "ballFaced": 0,
            "fours": 0,
            "sixes": 0,
            "strikeRate": 0,
            "oversBowled": 0,
            "runsConceded": 0,
            "economyRate": 0,
            "wickets": 0,
            "maiden": 0,
            "howToOut": "-",
            "catches": [],
            "stumping": [],
            "runout": [],
            "participatedRunout": []
        },
        {
            "_id": "1501201",
            "runsScored": 12,
            "ballFaced": 5,
            "fours": 1,
            "sixes": 1,
            "strikeRate": 240,
            "oversBowled": 2,
            "runsConceded": 28,
            "economyRate": 14,
            "wickets": 0,
            "maiden": 0,
            "howToOut": "c Rahul Mogri b Harshal Tupe",
            "catches": [
                "Chetan Tupe",
                "Kaustubh Tupe"
            ],
            "stumping": [],
            "runout": [],
            "participatedRunout": []
        },
        {
            "_id": "1501195",
            "runsScored": 74,
            "ballFaced": 27,
            "fours": 5,
            "sixes": 7,
            "strikeRate": 274.07,
            "oversBowled": 3,
            "runsConceded": 44,
            "economyRate": 14.67,
            "wickets": 0,
            "maiden": 0,
            "howToOut": "not out",
            "catches": [
                "Ashish Thantharatey"
            ],
            "stumping": [],
            "runout": [],
            "participatedRunout": []
        },
        {
            "_id": "1461428",
            "runsScored": 8,
            "ballFaced": 4,
            "fours": 0,
            "sixes": 1,
            "strikeRate": 200,
            "oversBowled": 3,
            "runsConceded": 29,
            "economyRate": 9.67,
            "wickets": 2,
            "maiden": 0,
            "howToOut": "run out Mayank / Sahil Raheja",
            "catches": [],
            "stumping": [],
            "runout": [],
            "participatedRunout": []
        },
        {
            "_id": "1461413",
            "runsScored": 23,
            "ballFaced": 12,
            "fours": 0,
            "sixes": 3,
            "strikeRate": 191.67,
            "oversBowled": 2,
            "runsConceded": 18,
            "economyRate": 9,
            "wickets": 0,
            "maiden": 0,
            "howToOut": "c Sumit Gandhi b Arun Stambhampelli",
            "catches": [
                "Arun Stambhampelli (c)"
            ],
            "stumping": [],
            "runout": [],
            "participatedRunout": []
        },
        {
            "_id": "1451183",
            "runsScored": 16,
            "ballFaced": 6,
            "fours": 2,
            "sixes": 1,
            "strikeRate": 266.67,
            "oversBowled": 2,
            "runsConceded": 11,
            "economyRate": 5.5,
            "wickets": 0,
            "maiden": 0,
            "howToOut": "c Syed Jamaal Nasir b Aman Deep",
            "catches": [
                "Mohan Slathia (c)"
            ],
            "stumping": [],
            "runout": [],
            "participatedRunout": []
        },
        {
            "_id": "1451132",
            "runsScored": 26,
            "ballFaced": 10,
            "fours": 1,
            "sixes": 3,
            "strikeRate": 260,
            "oversBowled": 3,
            "runsConceded": 18,
            "economyRate": 6,
            "wickets": 3,
            "maiden": 0,
            "howToOut": "c Javed b Ram Lomte",
            "catches": [
                "Saheb Desai"
            ],
            "stumping": [],
            "runout": [],
            "participatedRunout": []
        },
        {
            "_id": "1392788",
            "runsScored": 13,
            "ballFaced": 6,
            "fours": 2,
            "sixes": 0,
            "strikeRate": 216.67,
            "oversBowled": 3,
            "runsConceded": 30,
            "economyRate": 10,
            "wickets": 0,
            "maiden": 0,
            "howToOut": "not out",
            "catches": [
                "Sachin Patil"
            ],
            "stumping": [],
            "runout": [],
            "participatedRunout": [
                "Pankaj Rastogi"
            ]
        },
        {
            "_id": "1611380",
            "runsScored": 0,
            "ballFaced": 0,
            "fours": 0,
            "sixes": 0,
            "strikeRate": 0,
            "oversBowled": 0,
            "runsConceded": 0,
            "economyRate": 0,
            "wickets": 0,
            "maiden": 0,
            "howToOut": "-",
            "catches": [],
            "stumping": [],
            "runout": [],
            "participatedRunout": []
        },
        {
            "_id": "1602721",
            "runsScored": 0,
            "ballFaced": 0,
            "fours": 0,
            "sixes": 0,
            "strikeRate": 0,
            "oversBowled": 0,
            "runsConceded": 0,
            "economyRate": 0,
            "wickets": 0,
            "maiden": 0,
            "howToOut": "-",
            "catches": [],
            "stumping": [],
            "runout": [],
            "participatedRunout": []
        },
        {
            "_id": "1536540",
            "runsScored": 0,
            "ballFaced": 0,
            "fours": 0,
            "sixes": 0,
            "strikeRate": 0,
            "oversBowled": 0,
            "runsConceded": 0,
            "economyRate": 0,
            "wickets": 0,
            "maiden": 0,
            "howToOut": "-",
            "catches": [],
            "stumping": [],
            "runout": [],
            "participatedRunout": []
        },
        {
            "_id": "1501201",
            "runsScored": 0,
            "ballFaced": 0,
            "fours": 0,
            "sixes": 0,
            "strikeRate": 0,
            "oversBowled": 0,
            "runsConceded": 0,
            "economyRate": 0,
            "wickets": 0,
            "maiden": 0,
            "howToOut": "-",
            "catches": [],
            "stumping": [],
            "runout": [],
            "participatedRunout": []
        },
        {
            "_id": "1501195",
            "runsScored": 0,
            "ballFaced": 0,
            "fours": 0,
            "sixes": 0,
            "strikeRate": 0,
            "oversBowled": 0,
            "runsConceded": 0,
            "economyRate": 0,
            "wickets": 0,
            "maiden": 0,
            "howToOut": "-",
            "catches": [],
            "stumping": [],
            "runout": [],
            "participatedRunout": []
        },
        {
            "_id": "1461428",
            "runsScored": 0,
            "ballFaced": 0,
            "fours": 0,
            "sixes": 0,
            "strikeRate": 0,
            "oversBowled": 0,
            "runsConceded": 0,
            "economyRate": 0,
            "wickets": 0,
            "maiden": 0,
            "howToOut": "-",
            "catches": [],
            "stumping": [],
            "runout": [],
            "participatedRunout": []
        },
        {
            "_id": "1461413",
            "runsScored": 0,
            "ballFaced": 0,
            "fours": 0,
            "sixes": 0,
            "strikeRate": 0,
            "oversBowled": 0,
            "runsConceded": 0,
            "economyRate": 0,
            "wickets": 0,
            "maiden": 0,
            "howToOut": "-",
            "catches": [],
            "stumping": [],
            "runout": [],
            "participatedRunout": []
        },
        {
            "_id": "1451183",
            "runsScored": 0,
            "ballFaced": 0,
            "fours": 0,
            "sixes": 0,
            "strikeRate": 0,
            "oversBowled": 0,
            "runsConceded": 0,
            "economyRate": 0,
            "wickets": 0,
            "maiden": 0,
            "howToOut": "-",
            "catches": [],
            "stumping": [],
            "runout": [],
            "participatedRunout": []
        },
        {
            "_id": "1451132",
            "runsScored": 0,
            "ballFaced": 0,
            "fours": 0,
            "sixes": 0,
            "strikeRate": 0,
            "oversBowled": 0,
            "runsConceded": 0,
            "economyRate": 0,
            "wickets": 0,
            "maiden": 0,
            "howToOut": "-",
            "catches": [],
            "stumping": [],
            "runout": [],
            "participatedRunout": []
        },
        {
            "_id": "1392788",
            "runsScored": 0,
            "ballFaced": 0,
            "fours": 0,
            "sixes": 0,
            "strikeRate": 0,
            "oversBowled": 0,
            "runsConceded": 0,
            "economyRate": 0,
            "wickets": 0,
            "maiden": 0,
            "howToOut": "-",
            "catches": [],
            "stumping": [],
            "runout": [],
            "participatedRunout": []
        }
    ],
    "__v": 0
}

注意：在本文档内的 score 数组中，索引 10 之后有重复的对象。

使用以下代码初始更新文档（在此之前，分数数组为空）：

await Scorecard.findOneAndUpdate(
        { _id: fielder.player_id, },
        {
          $addToSet: {
            "score": {
              _id: matchID
            }
          }
        }
      );

稍后在代码中，分数数组中的对象再次更新以更改初始未更改字段的默认值（在猫鼬模式中设置）。

但是，问题是当上面引用的代码在一段时间后再次运行时，它会复制数组中的所有对象。我知道，还有其他类似的问题，但我是 mongodb 的初学者，无法制作复杂的聚合管道。非常感谢任何帮助。

【问题讨论】：

我们也可以知道您提供的参数的内容吗？即matchID
我应该与您分享有关 matchID 的哪些信息
@ray 对于提到的文档，它的值为658016。
@ray matchID 对于所有对象都是唯一的，但是重复会导致具有特定 ID 的对象出现两次或三次，具体取决于多少次，我允许函数运行
我不确定我们是否可以复制您的问题。在this trial in playground 中，它应该只能插入一个只有1 个字段_id 的对象。在我看来，可能需要提供一些其他内容来复制您的问题。

标签： node.js mongodb mongoose mongodb-query aggregation-framework

【解决方案1】：

$addToSet 运算符仅在数组不存在的情况下添加一个元素。

该数组中的每个元素都是一个对象。对象按照https://docs.mongodb.com/manual/reference/bson-type-comparison-order/#objects 的 mongodb 文档中的描述进行比较基本上，如果两个对象具有完全相同的字段、以完全相同的顺序、每个对象具有完全相同的值，则它们是相等的。换句话说，如果它们不相同，它们就不相等。

我在问题的数组中看不到任何重复项。 _id 字段有一些具有相同值，但它们包含其他几个不同的字段，因此它们不是重复的。

如果您需要更新数组中某个对象的值，还有其他几个关于修改嵌套文档的问题。

我怀疑您要做的是检测数组中是否已存在具有该 ID 的对象，如果已预设则更新，如果不存在则插入。
在这种情况下，您可以尝试使用管道形式的更新，以及 filter 和 mergeObjects 运算符。

【讨论】：