如何在嵌套数组中返回我要查找的元素? [英] How can I return the element I'm looking for inside a nested array?

问题描述

我有一个这样的数据库:

<预><代码>[{宇宙":漫画"，传奇":[{名称":x战警"，字符":[{字符":金刚狼"，图片":618035022351.png"},{字符":独眼巨人"，图片":618035022352.png"}]}]},{宇宙":dc"，传奇":[{名称":蜘蛛侠"，字符":[{字符":毒液"，图片":618035022353.png"}]}]}]

使用此代码，我设法更新了数组中的一个对象.特别是 character: wolverine

所在的对象

db.mydb.findOneAndUpdate({宇宙":漫画"，saga.name":x战警"，saga.characters.character":金刚狼"}, {$set:{saga.$[].characters.$[].character":lobezno"，saga.$[].characters.$[].picture":618035022354.png"，}}, {新:假})

它返回我所有的文档，我只需要匹配的文档

我想返回我更新的对象，而不必对数据库进行更多查询.

注意

有人告诉我，我的代码不能正常工作，显然我的查询更新不好，我想知道如何修复它并获取与这些搜索条件匹配的对象.

换句话说，我怎样才能得到这个输出:

<代码> {字符":金刚狼"，图片":618035022351.png"}

在使用过滤器的单个查询中

<代码> {宇宙":漫画"，saga.name":x战警"，saga.characters.character":金刚狼"}

我的 MongoDB 知识使我无法纠正这一点.

解决方案

使用 shell 方法 findAndModify 以满足您的需求.

但是您不能使用位置字符 $ 在 MongoDb 中投影时不止一次，因此您可能必须在客户端自己跟踪它.

使用 arrayFilters 更新深层嵌套的子文档，而不是位置所有操作符 $[].

下面是一个有效的查询 -

var 查询 = {宇宙:'漫画'};变量更新 = {$set:{'saga.$[outer].characters.$[inner].character': 'lobezno','saga.$[outer].characters.$[inner].picture': '618035022354.png',}};var 字段 = {'传奇人物':1};var updateFilter = {数组过滤器:[{'outer.name': 'x战警'},{'inner.character': '金刚狼'}]};db.collection.findAndModify({询问，更新，领域，数组过滤器:updateFilter.arrayFilters新:真实});

I have a database like this:

[
   {
      "universe":"comics",
      "saga":[
         {
            "name":"x-men",
            "characters":[
               {
                  "character":"wolverine",
                  "picture":"618035022351.png"
               },
               {
                  "character":"cyclops",
                  "picture":"618035022352.png"
               }
            ]
         }
      ]
   },
   {
      "universe":"dc",
      "saga":[
         {
            "name":"spiderman",
            "characters":[
               {
                  "character":"venom",
                  "picture":"618035022353.png"
               }
            ]
         }
      ]
   }
]

and with this code I manage to update one of the objects in my array. specifically the object where character: wolverine

db.mydb.findOneAndUpdate({
        "universe": "comics",
        "saga.name": "x-men",
        "saga.characters.character": "wolverine"
    }, {
        $set: {
            "saga.$[].characters.$[].character": "lobezno",
            "saga.$[].characters.$[].picture": "618035022354.png",

        }
    }, {
        new: false
    }

)

it returns all my document, I need ONLY the document matched

I would like to return the object that I have updated without having to make more queries to the database.

Note

I have been told that my code does not work well as it should, apparently my query to update this bad, I would like to know how to fix it and get the object that matches these search criteria.

In other words how can I get this output:

           {
              "character":"wolverine",
              "picture":"618035022351.png"
           }

in a single query using filters

    {
     "universe": "comics",
     "saga.name": "x-men",
     "saga.characters.character": "wolverine"
    }

My MongoDB knowledge prevents me from correcting this.

解决方案

Use the shell method findAndModify to suit your needs.

But you cannot use the positional character $ more than once while projecting in MongoDb, so you may have to keep track of it yourself at client-side.

Use arrayFilters to update deeply nested sub-document, instead of positional all operator $[].

Below is a working query -

var query = {
    universe: 'comics'
};

var update = {
    $set: {
        'saga.$[outer].characters.$[inner].character': 'lobezno',
        'saga.$[outer].characters.$[inner].picture': '618035022354.png',
    }
};

var fields = {
    'saga.characters': 1
};

var updateFilter = {
    arrayFilters: [
        {
            'outer.name': 'x-men'
        },
        {
            'inner.character': 'wolverine'
        }
    ]
};

db.collection.findAndModify({
    query,
    update,
    fields,
    arrayFilters: updateFilter.arrayFilters
    new: true
});

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