如何在 mongo db 中获取所有数字类型的属性？

Question

我需要提取所有数字类型的属性。 例如，如果不同的属性是

{ 年龄：32 性别：“女性” 年份：2020 姓名：“Abc” }

我的查询应该返回 ["age","year"]

Answer 1

我认为以下查询应该可以帮助您。

db.test.aggregate([
    // Remove this `$limit` stage if your Collection schema is dynamic and you want to process all the documents instead of just one
    {
        "$limit": 1
    },
    {
        "$project": {
            "arrayofkeyvalue": {
                "$filter": {
                    "input": {"$objectToArray":"$$ROOT"},
                    "as": "keyValPairs",
                    "cond": {
                        "$in": [{"$type": "$$keyValPairs.v"}, ["double", "int", "long"]],
                        // Change the above line to the following to get only `int` keys instead of `int, double` and `long`:
                        // "$eq": [{"$type": "$$keyValPairs.v"}, "int"],
                    }
                }
            }
        }
    },
    {
        "$group": {
            "_id": null,
            "unique": {"$addToSet": "$arrayofkeyvalue.k"}
        }
    },
    {
        "$project": {
            "_id": 0,
            "intKeyNames": {
                "$reduce": {
                    input: "$unique",
                    initialValue: [],
                    in: {$setUnion : ["$$value", "$$this"]}
                }
            }
        }
    },
])

上面的查询结果会是这样的：

{
    "intKeyNames" : [
        "_id",
        "abc",
        "paymentMonth",
        "paymentYear",
        "value"
    ]
}