mongocxx bsoncxx new c++11 driver: Extracting Values from bson without knowing the key's name

[javantamt]

Hey there,
I'm reciving a JSON from an application. I know the structure, but not the names of the keys. I'm going to extract the URL's, which are placed in the arrays.
But I don't know the names of the key's of the subdocument. So I can't access them like here:

auto ArrayToExtract =MayDocumentView["file"][???];

Using numbers is assuming an offset in an array and no key. It's return value is a bsoncxx::array::element and not a document::element.

// My JSON
{
    "file": {
        "khjasdnkas": ["MyURL_1t", "MyURL_2t", "MyURL_3t"],
        "glasdjlasd": ["MyURL_1tp", "MyURL_3tp"]
        "more......": [ "... unknown number of elements ..." ]
    }
}

If i have the arrays, I know how to extract the elements one by one as a string:

Call: ElementExtract(MaArray[i], &MyString);

int ElementExtract(bsoncxx::document::element eleDUT, std::string * strStringVal){

  int iErr = 0;
  strStringVal->clear();

  if (! eleDUT) {
    iErr = 1;   // element searched does not exist
  } else {
    // checking if type correct
    if (eleDUT.type() != bsoncxx::types::b_utf8::type_id) {
      iErr = 2; // element searched, is found, but has not the right value.
    }else{
      // Extract the string  
      strStringVal->append( eleDUT.get_utf8().value.to_string() );
    }
  }

  return iErr;
}

[javantamt]

I've to correct my self. The function can only handle document::element, no array::element.
A document::element is a key & Value and a Array Element is only a value?

[javantamt]

SOLVED:
use the force of iterators...

bsoncxx::builder::stream::document MyBuilderTmp = document{};

bsoncxx::document::value blubb = MyBuilderTmp << "Key1" << "Val1" << "Key2" << "Val2" << finalize;
bsoncxx::document::view MyBlubbView = blubb.view();

std::cout << to_json(MyBlubbView) << std::endl;

 auto size = MyBlubbView.length();
 auto MyBegin = MyBlubbView.begin();
 auto MyEnd = MyBlubbView.end();
 auto num = std::distance(MyBegin,MyEnd);
 auto Mykey = MyBegin->key();
 auto Myval = MyBegin->get_utf8().value.to_string();
 MyBegin++; // it's no more my begin.
 auto Mykey2 = MyBegin->key();
 // make shure bevore calling this function that the value is a string indeed.
 // Otherwise Runtime say's: No no no!
 auto Myval2 = MyBegin->get_utf8().value.to_string();

 std::cout
 << "\nSize of structure: " << size
 <<"\nNum Keys: " << num
 <<"\nMy Keys: " << Mykey
 << " val:  " << Myval
 << "\nnext Key: " << Mykey2
 << " and its value: " << Myval2
 << std::endl;

Output:

{
    "Key1" : "Val1",
    "Key2" : "Val2"
}

Size of structure: 35
Num Keys: 2
My Keys: Key1 val:  Val1
next Key: Key2 and its value: Val2