jquery - How do i use the mongo query and traverse the mongo(JSON)document and fetch the element by key -

how use mongo query , traverse multiple array , fetch value of key. here json

{     "_id" : "t5zcjquysxcshodjg",     "original" : {             "name" : "images (1).jpg",             "updatedat" : isodate("2015-03-18t11:48:33.124z"),             "size" : 10881,             "type" : "image/jpeg"     },     "uploadedat" : isodate("2015-08-16t13:13:35.392z"),     "copies" : {             "uploads" : {                     "name" : "images (1).jpg",                     "type" : "image/jpeg",                     "size" : 10881,                     "key" : "uploads-t5zcjquysxcshodjg-images (1).jpg",                     "updatedat" : isodate("2015-08-16t13:13:35z"),                     "createdat" : isodate("2015-08-16t13:13:35z")             }     } 

i want fetch value of size. example can fetch value of uploadedat below

 db.cfs.uploads.filerecord.find({},{uploadedat:1}).pretty() 

like vise have value of size how query should ?

the query can whatever want return document. {}, example. can use projection second parameter of find() method, limit amount of data returned.

when have valid doc object, can use doc.original.size access property want.

in mongo shell:

var cursor =  db.cfs.uploads.filerecord.find({}, { "original.size": 1}) var doc = cursor.next() // { "_id" : "t5zcjquysxcshodjg", "original" : { "size" : 10881 } } var size = doc.original.size // 10881