无法使用 Object.keys(doc).forEach 读取未定义的属性

Question

我收到“无法读取未定义的属性‘重复’”错误，但在控制台日志记录中，似乎对象已明确定义，因此我不知道代码为什么会崩溃。

这是doc对象的控制台日志：

RESULT DOC: { _id: 5d9bc5c2bbb87318847cef91,
  authData:
   { dateEffective: { attr: [Object], value: [] },
     username: { attr: [Object], value: [Array] },
     password: { attr: [Object], value: [Array] },
     mainEmail: { attr: [Object], value: [Array] },
     _id: 5d9bc5c2bbb87318847cef86 },
  nameData:
   { title: { attr: [Object], value: [Array], enum: [Array] },
     firstName: { attr: [Object], value: [Array] },
     middleName: { attr: [Object], value: [Array] },
     familyName: { attr: [Object], value: [Array] },
     suffix: { attr: [Object], value: [Array], enum: [Array] },
     _id: 5d9bc5c2bbb87318847cef87 }
. . .
. . .

这是meta的控制台日志：

META: { authData:
   { label: 'Authentication',
     depth: 4,
     hidden: false,
     repeats: false },
  nameData: { label: 'Name', depth: 5, hidden: false, repeats: false },
. . . 
. . . 
}

users_controller.js - 有问题的路线。 . .

    exports.user_details_post = [(req, res, next)=> {
        //LOG
        console.log(`Request: ${util.inspect(req.body)}`); // <-- ALL GOOD HERE
        next();
        },
        //VALIDATE
        body('email', 'Must be valid email.').isLength({min: 5}).trim(),
        //SANITIZE
        sanitizeBody('*').escape(),
        //SAVE
        (req,res, next) =>{
            let user = UserObj.findById(req.params.id, function(err,doc){
                const errors = validationResult(req);
                let activeArr = [];
                let maxActive = 0;

                if (err) {}
                console.log(`RESULT DOC: ${util.inspect(doc)}`); // <-- ALL GOOD HERE. DOC APPEARS WELL-FORMED
                Object.keys(doc).filter(sec=>sec!=="_id" && sec!=="__v").forEach(sec=>{
                    console.log(`SEC: ${util.inspect(sec)}`); // <-- PROBLEM HERE! 
                                                              // "Sec" is "$___", but should be 
                                                              // "authData", "nameData", etc. 
                                                              // Note, I also tried 
                                                              // "Object.keys(JSON.parse(doc)).filter.  
                                                              // but that didn't work either
                    if (!!meta[sec].repeats) {                // CRASHES HERE. "Meta" is well-defined,                                      
                                                              // and has fields "authData", "emailData",
                                                              // etc., but "sec" seems to be problematic
                        Object.keys(sec).forEach(fld=> {

. . . 
. . .
                }
            })
    }];

显然，Object.keys(doc).forEach(sec=> . . . ) 构造似乎有问题，因为 sec 以 $___ 而不是 authData、nameData 等出现。我是否允许遍历 Object.keys(doc)，如果是这样我做错了什么？

Answer 1

与其过滤特定的key，不如先检查meta中是否存在key。

Object.keys(doc).forEach(sec => {
    if (meta.hasOwnProperty(sec) && meta[sec].repeats) {
        ...
    }
});