{
        "_id" : ObjectId("5a4e43edb85ed11cd4dcba45"),
        "email" : "av@gmail.com",
        "username" : "alpesh",
        "subscriptions" : [ 
            {
                "sub_id" : "5a4df654b9799b79147f9361",
                "activation_date" : ISODate("2017-12-19T18:30:00.000Z"),
                "expiry_date" : ISODate("2018-01-19T18:30:00.000Z")
            }, 
            {
                "sub_id" : "5a4df654b9799b79147f9361",
                "activation_date" : ISODate("2018-01-19T18:30:00.000Z"),
                "expiry_date" : ISODate("2018-02-19T18:30:00.000Z")
            }, 
            {
                "sub_id" : "5a51a925ddc5003b68cc38b3",
                "activation_date" : ISODate("2018-02-19T18:30:00.000Z"),
                "expiry_date" : ISODate("2018-03-22T18:30:00.000Z")
            }
        ]
    }

这个我试过了 db.find({"subscriptions.sub_id": "5a4df654b9799b79147f9361"}); 它返回..

{
    "_id" : ObjectId("5a4e43edb85ed11cd4dcba45"),
    "email" : "av@gmail.com",
    "username" : "alpesh",
    "subscriptions" : [ 
        {
            "sub_id" : "5a4df654b9799b79147f9361",
            "activation_date" : ISODate("2017-12-19T18:30:00.000Z"),
            "expiry_date" : ISODate("2018-01-19T18:30:00.000Z")
        }, 
        {
            "sub_id" : "5a4df654b9799b79147f9361",
            "activation_date" : ISODate("2018-01-19T18:30:00.000Z"),
            "expiry_date" : ISODate("2018-02-19T18:30:00.000Z")
        }, 
        {
            "sub_id" : "5a51a925ddc5003b68cc38b3",
            "activation_date" : ISODate("2018-02-19T18:30:00.000Z"),
            "expiry_date" : ISODate("2018-03-22T18:30:00.000Z")
        }
    ]
}

我也尝试了 $aggregate 、 $unwind 、 $filter 、 $projection 和许多方法，但没有一个像预期的那样返回... 我想要所有匹配的子文档...像这样....

   {
        "_id" : ObjectId("5a4e43edb85ed11cd4dcba45"),
        "email" : "av@gmail.com",
        "username" : "alpesh",
        "subscriptions" : [ 
            {
                "sub_id" : "5a4df654b9799b79147f9361",
                "activation_date" : ISODate("2017-12-19T18:30:00.000Z"),
                "expiry_date" : ISODate("2018-01-19T18:30:00.000Z")
            }, 
            {
                "sub_id" : "5a4df654b9799b79147f9361",
                "activation_date" : ISODate("2018-01-19T18:30:00.000Z"),
                "expiry_date" : ISODate("2018-02-19T18:30:00.000Z")
            }
        ]
    }

最佳答案

db.collection('gyms').aggregate([
    {
        $match: {
            subscriptions: { 
                $elemMatch: { sub_id: "5a4df654b9799b79147f9361" }
            }
        }
    },
    {
        $redact: {
            $cond: {
                if: {
                    $or: [
                        { $eq: ["$sub_id", "5a4df654b9799b79147f9361" ] },
                        { $not: "$sub_id" }
                    ]
                },
                then: "$$DESCEND",
                else: "$$PRUNE"
            }
        }
    }
])

这是在单个文档中按预期生成的，没有不必要的子文档。

{
    "email": "av@gmail.com",
    "username": "alpesh",
    "subscriptions": [
        {
            "sub_id": "5a4df654b9799b79147f9361",
            "activation_date": "2017-12-19T18:30:00.000Z",
            "expiry_date": "2018-01-19T18:30:00.000Z"
        },
        {
            "sub_id": "5a4df654b9799b79147f9361",
            "activation_date": "2018-01-19T18:30:00.000Z",
            "expiry_date": "2018-02-19T18:30:00.000Z"
        }
    ]
}

关于mongodb - MongoDB子文档过滤，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/48134799/