javascript - 在 meteor 中插入嵌套对象

Question

我将此文档保存在名为 exam 的 mongo 集合中

// meteor:PRIMARY> db.exam.find()
{
    "_id" : "RLvWTcsrbRXJeTqdB",
    "examschoolid" : "5FF2JRddZdtTHuwkx",
    "examsubjects" : [
        {
            "subject" : "Z4eLrwGwqG4pw4HKX"
        },
        {
            "subject" : "fFcWby8ArpboizcT9"
        }
    ],
    "examay" : "NrsP4srFGfkc5cJkz",
    "examterm" : "5A5dNTgAkdRr5j53j",
    "examclass" : "gYF2wE4wBCRy9a3ZC",
    "examname" : "First",
    "examdate" : ISODate("2016-05-07T22:41:00Z"),
    "examresultsstatus" : "notreleased"
}

我正在尝试从此文档中选择数据并使用此代码将其保存到另一个文档中。目的是让上面文档中的 examsubjects 值成为我要插入的文档中的键进入。

'click .reactive-table tr': function() {
    Session.set('selectedPersonId', this._id);
    var cursor = Exam.find({ _id:
            Session.get("selectedPersonId")}).fetch();
    cursor.forEach(function(doc){
        for (i = 0; i < doc.examsubjects.length; i++) {
            for (var prop in doc.examsubjects[i]) {
                console.log("obj." + prop + " = " + doc.examsubjects[i][prop]);
                var subj = doc.examsubjects[i][prop];
                Told.insert({
                    examschoolid:"sms",
                    examname:doc.examname,
                    examsubjects: [{subj : "0"}],
                    examay:doc.examay,
                    examterm:doc.examterm,
                    examclass:doc.examclass,
                    examdate:doc.examdate
                });
            }
        }
    });
},

当代码运行时，保存 subjects 值的变量 subj 只是插入 subj 而不知道它是这样的变量

{
    "_id" : "5yjwFanBAupgu9GHq",
    "examschoolid" : "sms",
    "examname" : "First",
    "examsubjects" : [
        {
            "subj" : "0"
        }
    ],
    "examay" : "NrsP4srFGfkc5cJkz",
    "examterm" : "5A5dNTgAkdRr5j53j",
    "examclass" : "gYF2wE4wBCRy9a3ZC",
    "examdate" : ISODate("2016-05-07T22:41:00Z")
}

为什么变量不被视为变量？

编辑

'click .reactive-table tr': function() {
    Session.set('selectedPersonId', this._id);
    var cursor = Exam.find({ _id: Session.get("selectedPersonId")}).fetch();
    cursor.forEach(function(doc){

        var sq = function(){
            for (i = 0; i < doc.examsubjects.length; i++) {
                for (var prop in doc.examsubjects[i]) {
                    const subj = doc.examsubjects[i][prop];
                    let subject = {};
                    subject[subj] = "0";
                    return [subject];

                }
            }
        }
        console.log(sq());
        Told.insert({
            examschoolid:"sms",
            examname:doc.examname,
            examsubjects: sq(),
            examay:doc.examay,
            examterm:doc.examterm,
            examclass:doc.examclass,
            examdate:doc.examdate
        });

    });
    //Uncaught TypeError: cursor.count is not a function
},

更新后的代码几乎可以工作，但只插入了 1 条记录。

Answer 1

这就是 JSON 的工作原理，它从字面上获取键。使用 ES6 括号表示法修复它:

examsubjects: [{
  [subj] : "0"
}],