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arrays - 在嵌套数组 MongoDB 中更新或插入新数据

问题描述

我正在使用 Node JS 和 Mongoose 仅​​供参考。鉴于我有这样的事情： -

let people = [
    {
        "_id": 1,
        "name": "Person 1",
        "pets": [
            {
                "_id": 1,
                "name": "Tom",
                "category": "cat",
                "favFood": [
                    {
                        "_id": 1,
                        "name": "steamed fish"
                    }
                ]
            },
            {
                "_id": 2,
                "name": "Jerry",
                "category": "mouse",
                "favFood": [
                    {
                        "_id": 1,
                        "name": "cheese"
                    }
                ] 
            }
        ]
    }
]

现在我知道如何获得如下所示insert的新pet数据：-

// new Pet Data to INSERT
let newPetData = {
    name: "Butch",
    category: "dog",
    favFood: [
        {
            name: "bone"
        }
    ]    
}

// INSERT new data in DB
People.updateOne(
    // push into the sub-documents - pets
    { $push: { pets: newPetData } },
    (err, success) => {
        if(err) res.json({ message: `Unsuccessful!`, report: err })
        else res.json({ message: `Successful!`, report: success })
    }
)

但是如果我有他们的（宠物的id），我怎么能插入新favFood的数据呢？petid 

let petID = 1 // this is the ID of pet named Tom

// this is a new favorite food of Tom to INSERT
let newFavFood = {
    name: "fried fish"
}

// code to INSERT new favorite food of Tom (THIS DOES NOT WORK!)
People.updateOne(
    { "_id": petID } // id of pet 'Tom'
    { $push: { favFood: newFavFood } }, // push into the sub-documents - favFood
    (err, success) => {
        if(err) res.json({ message: `Unsuccessful!`, report: err })
        else res.json({ message: `Successful!`, report: success })
    }
)

上面的代码不起作用。我认为，如果我指定id上面显示的宠物，{ "_id": petID }就会产生我想要的东西。即使它返回一个messageof Successful!。但仍然没有新记录添加到数据库本身。我正在寻找的结果如下所示：-

let people = [
    {
        "_id": 1,
        "name": "Person 1",
        "pets": [
            {
                "_id": 1,
                "name": "Tom",
                "category": "cat",
                "favFood": [
                    {
                        "_id": 1,
                        "name": "steamed fish"
                    },
                    {
                        "_id": 2, 
                        "name": "fried fish" // this is the new data inserted
                    }
                ]
            },
            {
                "_id": 2,
                "name": "Jerry",
                "category": "mouse",
                "favFood": [
                    {
                        "_id": 1,
                        "name": "cheese"
                    }
                ] 
            }
        ]
    }
]

有没有其他方法可以做到这一点？我必须$elemMatch在此实施吗？如果是这样，我怎么能在这里做到这一点？

标签： arraysmongodbnestedmongodb-queryinsert-update

解决方案

查询部分匹配文档，而不是元素，因此{ "_id": petID }匹配人员的_id。要匹配宠物，请使用点符号，例如{ "pets._id": petID }

然后使用位置运算符$引用与查询部分匹配的第一个数组元素：

.updateOne(
    { "pets._id": petID },
    { $push: { "pets.$.favFood": newFavFood }}
)

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