MongoDB：如何在不知道字段名称的情况下读取值？

Question

I have a collection "A" that have documents:

{_id:1, a1: "degree"}
{_id:2, a2: "score"} ...

I need to transform that collection to key-value structure such as:

{_id: x, {name: "a1",  label: "degree"} }
{_id: y, {name: "a2",  label: "score"} }

Problem is every document can have different field name in collection A. To get the field name, I can use javascript as follows,
But still can't find way to get each field value without knowing field name.

var arr = new Array()
var x = 0
var cur = db."A".find()
while( cur.hasNext() ) {
  var i = 0
  for( var field in cur[x] ) {
      arr[i] = field;    // get field name
      i++;}
db."B".save( { "name": arr[1], //fieldname
             "label":    //how to put value without knowing field name?
            )
  x++;
}

Do you have any idea how to get field value without knowing the name?
thank you.

Answer 1

I'm not sure is this what you really want but hope this help.

Try this :

var obj = [
    {_id: x, {name: "a1",  label: "degree"} },
    {_id: y, {name: "a2",  label: "score"} }
];

for (index in obj) {
    for (key in obj[index]) {
        console.log(key); 
        console.log(obj[index][key]); 
    }
}

Answer 2

Thanks for comments and answers! I have completed my javascript code as follows:

var arr = new Array()
var x = 0
var cur = db.A.find()
while( cur.hasNext() ) {
var i = 0
for( var field in cur[x] ) {
    arr[i] = field;    // get field name
    print( "field name="+ field);
    print( "the value="+cur[x][field] );
    i++;
    }
x++;
}