在嵌套数组 MongoDB 中更新或插入新数据

Question

我将 Node JS 与 Mongoose 一起使用，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insert new 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 })
    }
)    

上面的代码不起作用。我认为如果我指定{ "_id": petID } 上方的宠物的id 会产生我想要的。即使它返回 message 或 Successful!。但是 没有向 db 本身添加新记录。我正在寻找的结果将是如下所示：-

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？我必须在此实施$elemMatch 吗？如果是这样，我该怎么做？

Answer 1

查询部分匹配文档，而不是元素，所以{ "_id": petID } 匹配人的_id。要匹配宠物，请使用{ "pets._id": petID }等点符号

然后使用位置运算符$ 引用第一个匹配查询部分的数组元素：

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