在嵌套数组 MongoDB 中更新或插入新数据

Question

我正在使用 Node JS 和 Mongoose fyi。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insert新pet数据如下所示:-

// 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 id （宠物的 ID），我该如何插入 pet 的新 favFood 数据？

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 })
    }
)

以上代码无效。我想如果我指定宠物的 id 就像上面的节目 { "_id": petID } 会产生我想要的。尽管它 returns 是 Successful! 的 message。但是没有新记录添加到 db 本身。我要寻找的结果是 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？我必须在其中实施 $elemMatch 吗？如果是这样，我怎么能在这里做到这一点？

Answer 1

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

然后使用位置运算符$引用匹配查询部分的第一个数组元素：

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

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