Object.keys()从集合中返回MongoDB对象上的意外键 [英] Object.keys() returns unexpected keys on MongoDB object from collection
问题描述
在这里处理一个奇怪的问题.这是从mongodb中提取并传递给以下函数的对象数组.
Working with a strange problem here. This is an array of objects which is pulled from mongodb and passed into the following function.
我在从数据库中拉出的阵列的forEach中依次尝试了以下3个日志:
I tried the following 3 logs sequentially within the forEach on the array pulled from the database:
-
e(数组中的对象元素)可以正确返回.如您所见，所有属性(键)都存在:
e(the object element within the array) which returns correctly. as you can see all the properties (keys) exist:
{ paid: false,
hotelWebsite: 'www.testing.com',
_id:5951848a24bb261eed09d638,
hotelAddress: '123 easy street',
...etc }
-
console.log(Object.keys(e))返回的不是键... console.log(Object.keys(e))is returning things that are not the keys...
[ '__parentArray',
'__parent',
'__index',
'$__',
'isNew',
'errors',
'_doc',
'$init' ]
- 最后:
for(key in e){
console.log(key);
}
返回绝对的数据混乱，其中一部分包含对象的实际键:
which returns an absolute mess of data, part of which DOES contain the actual keys of the object:
__parentArray
__parent
__index
$__
isNew
errors
_doc
$init
id
_id
hotelWebsite
hotelAddress
hotelNumber
hotelName
courseCost
courseDate
courseState
courseCity
courseName
paid
studentComments
studentEmail
studentPhone
studentCountry
studentZip
studentState
studentCity
studentAddress
studentCompany
studentName
schema
constructor
$__original_remove
remove
_pres
_posts
$__original_validate
validate
toBSON
markModified
populate
save
update
inspect
invalidate
$markValid
$isValid
ownerDocument
$__fullPath
parent
parentArray
on
once
emit
listeners
removeListener
setMaxListeners
removeAllListeners
addListener
$__buildDoc
init
$hook
$pre
$post
removePre
removePost
_lazySetupHooks
set
$__shouldModify
$__set
getValue
setValue
get
$__path
unmarkModified
$ignore
modifiedPaths
isModified
$isDefault
isDirectModified
isInit
isSelected
isDirectSelected
$__validate
validateSync
$__reset
$__dirty
$__setSchema
$__getArrayPathsToValidate
$__getAllSubdocs
$__handleReject
$toObject
toObject
toJSON
toString
equals
execPopulate
populated
depopulate
以及相关代码示例(如果需要):
And a relevant sample of the code if needed:
studentsArray.forEach( (e, i) => {
if(task === 'nameTag'){
console.log(e);
console.log(Object.keys(e));
for(k in e){
console.log(k);
}
}
....
我需要访问属性(键)以在forEach函数中进行进一步处理.我对造成这种情况的原因非常困惑，并且从未遇到过此类问题.为了记录，对象存在，使用console.log(typeof e)表示对象是对象(而不是数据字符串").我可以使用点或括号符号来访问属性，但不能使用Object.keys()或for (keys in obj).
I need access to the properties (keys) for further processing within the forEach function. I am very confused on what is causing this and have never run into this sort of issue before. For the record the objects exist, using a console.log(typeof e) it IS an object (not a data "string"). I can access the properties using the dot or bracket notation but NOT using Object.keys() or for (keys in obj).
有人可以帮我解决这个问题吗?
Can anyone help me sort this out please?
推荐答案
for ... in iterates all enumerable properties, both own and inherited. This is not "a strange bug," this is in fact the intended behavior.
对于Object.keys()，除非它由不兼容的实现覆盖，否则实际上它们是对象本身的可枚举键，因此您很可能会误解. e对象具有 .toJSON() 方法在其原型中会在执行console.log(e)时隐式调用，因此可能是您在此处看到的输出，并且不太可能反映出与原始对象完全相同的属性键.尝试调用console.log(e.toJSON())，我想它的输出将与第一个相同.
As for the Object.keys(), unless it was overwritten by a non-compliant implementation, those are in fact enumerable keys of the object itself, so you are most likely mistaken. The e object has a .toJSON() method in its prototype that is implicitly called when you do console.log(e), so that is probably the output you are seeing there, and is not likely going to reflect exactly the same property keys as the original object. Try calling console.log(e.toJSON()) and I'm guessing it will be the same output as in the first one.
If you want only the object's own properties, use Object.getOwnPropertyNames(e).
如果要在第一个输出中打印键，请使用Object.keys(e.toJSON()).
If you want the keys printed in the first output, then use Object.keys(e.toJSON()).
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