在流星中插入嵌套对象

Question

我将此文档保存在我的 mongo 集合中，名为 exam

// 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。

'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，保存主题值的变量subj 只是插入了不知道它是这样的变量的 subj

{
    "_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"
}],

Answer 2

这是因为它被视为文字对象中的键。

如果您想将subj 的值作为您的键，则需要使用括号表示法，预先创建对象：

const subj = doc.examsubjects[i][prop];
let subject = {};
subject[subj] = "0";

Told.insert({
    examschoolid:"sms",
    examname:doc.examname,
    examsubjects: [subject],
    ...
});