使用日期作为mongodb中的键值

Question

我正在研究一个简单的考勤系统，该系统应该具有这样的结构

{
    "_id" : ObjectId("5a800c280856ed210f6553cb"),
    "class" : 1,
    "subject" : {
        "maths" : {
            "grammer" : "0",
            "spelling" : "0",
            "marks" : 25
        },
        "science" : {
            "grammer" : "1",
            "spelling" : "1",
            "marks" : 21
        },
        "history" : {
            "grammer" : "1",
            "spelling" : "1",
            "marks" : 28
        }
    },
    "name" : "max",
    "roll no" : 10
}

我想要做的是创建另一个出勤领域，如下所示

{
        "_id" : ObjectId("5a800c280856ed210f6553cb"),
        "class" : 1,
        "subject" : {
            "maths" : {
                "grammer" : "0",
                "spelling" : "0",
                "marks" : 25
            },
            "science" : {
                "grammer" : "1",
                "spelling" : "1",
                "marks" : 21
            },
            "history" : {
                "grammer" : "1",
                "spelling" : "1",
                "marks" : 28
            }
        },
        "name" : "max",
        "roll no" : 10
        "attendace":{"Tue Feb 11 2018 12:14:36 GMT+0530 (IST)": 1,
                     "Tue Feb 12 2018 12:14:36 GMT+0530 (IST)": 1, 
                     "Tue Feb 13 2018 12:14:36 GMT+0530 (IST)": 1
                     }

    }

我尝试了以下命令，但它无法正常工作

db.candidates.update({"_id" : ObjectId("5a800c280856ed210f6553cb") },{$set : {"attendance":{Date():1}}})  

非常感谢任何帮助

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