通過ID查找mongo子集合

Question

我需要有關此查詢的幫助。 我如何找到子集合？

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db.clientes.find({
    _id: ObjectId("587cc2d8704ae610d3741e6b")
}); {
    "_id": ObjectId("587cc2d8704ae610d3741e6b"),
    "razonSocial": "CREXELL",
    "cuit": "20-12121212-0",
    "vsat": [{
        "CPA": 8682,
        "IP": "149.126.35.61"
    }, {
        "CPA": 5500,
        "IP": "149.126.36.109",
        "_id": ObjectId("587cdb2af073f02a251361e8")
    }, {
        "CPA": 1234,
        "IP": "1902312",
        "_id": ObjectId("587d05fb930d504018ef8e01")
    }],
    "__v": 7
}

我需要得到像這樣的東西：

{
            "CPA": 5500,
            "IP": "149.126.36.109",
            "_id": ObjectId("587cdb2af073f02a251361e8")
        }

感謝：D

Answer 1

您可以使用聚合來實現此目的，但是您還需要知道子文檔數組中要查找的_id。

db.clientes.aggregate([
    // Find the document matching the _id only
    { $match: { "_id": ObjectId("587cc2d8704ae610d3741e6b") } },
    // Split all vsat array elements into separate documents
    { $unwind: "$vsat" },
    // Match only the case where the _id matches 587cdb2af073f02a251361e8
    { $match: { "vsat._id": ObjectId("587cdb2af073f02a251361e8") } },
    // Choose the elements we wish to return
    { $project: { "vsat": 1, "_id": 0 } }
])

結果是：

{ 
    "vsat" : { 
        "CPA" : 5500, 
        "IP" : "149.126.36.109", 
        "_id" : ObjectId("587cdb2af073f02a251361e8") 
    } 
}