基於字段mongodb的共同值的分組集合

Question

我的收藏看起來像這樣

 { "email" : "tp@sd.com", "subscriptions" : [ { "default" : false, "interval" : "weekly", "tags" : [ { "name" : "group-1", "value" : "g1-value-1" }, { "name" : "group-1", "value" : "g1-value-2" }, { "name" : "group-2", "value" : "g2-value-1" }, { "name" : "group-3", "value" : "g3-value-1" }, { "name" : "group-3", "value" : "g3-value-2" } ] }, { "email":"lol@xyz.com", "subscriptions" : [ { "default" : false, "interval" : "weekly", "tags" : [ { "name" : "group-1", "value" : "g1-value-2" }, { "name" : "group-1", "value" : "g1-value-1" }, { "name" : "group-2", "value" : "g2-value-1" }, { "name" : "group-2", "value" : "g2-value-3" }, { "name" : "group-3", "value" : "g3-value-1" } ] } }

我想將其分組為包含電子郵件和常見組值的對象數組。

例如，用戶 1 有 g1-value-1，用戶 2 也有 g1-value-1，可能還有其他值。 但是這些用戶應該與他們的標簽一起分組。 我如何實現這一目標？

Answer 1

令人驚訝的是，這是一個非常簡單的查詢：

db.collection.aggregate([
    {
        $unwind: "$subscriptions"
    },
    {
        $unwind: "$subscriptions.tags"
    },
    {
        $group: {
            _id: "$subscriptions.tags.value",
            emails: {$addToSet: "$email"}
        }
    }
]); 

結果將如下所示：

[
    {
        _id: "g1-value-1",
        emails: [
            "tp@sd.com",
            "lol@xyz.com"
        ]
    },
    {
        _id: "g1-value-2",
        emails: [
            "tp@sd.com",
            "lol@xyz.com"
        ]
    },
    {
        _id: "g2-value-1",
        emails: [
            "tp@sd.com",
            "lol@xyz.com"
        ]
    },
    {
        _id: "g2-value-3",
        emails: [
            "lol@xyz.com"
        ]
    },
    {
        _id: "g3-value-1",
        emails: [
            "tp@sd.com",
            "lol@xyz.com"
        ]
    },
    {
        _id: "g3-value-2",
        emails: [
            "tp@sd.com",
        ]
    },
]